Cleaning Scratchy Bourns MOD pots


Jean-Paul
 

Bonjour a tous,

We have two fine SC502 scopes, scratchy controls V position, CH1/2 VAR, focus, Trig lev.

Many TEK Instruments of the era have sealed square modular controls, the Bourns MOD POTs.

The Best cleaner is DeoXit D-100 ?

But I do not have it, instead I have IPA, 99%, Miller Stephenson connector plus, contact renew, tuner lube/cleaner

Will any of these others penetrate the sealed and shaft bushings of the controls?

Or, must the Bourns Mod Post be opened up?

Many thanks,

Jon


satbeginner
 

Hi,

With the bourns potmeters you see a white or brown rectangle, that is the 3mm thick part that has the resistor track embedded.

What I did was:

A bit more to the front, like 1-2mm away from that rectangle, I drilled a tiny hole, using a 0.8mm hand drill, used in model building.

Important:
Make sure the potmeter is at the beginning of at the end of the track, to avoid you little drill damaged the moving contact when you penetrate the potmeter housing using your drill.

Also avoid going deep into the potmeter when drilling, you will feel when you are close to penetrating the wall of the potmeter.

Once done, you have a little hole where you can spray in your cleaner/lubricant of your choice.

This way you can avoid taking out the potmeter out of the scope.
Worked for me on my 485 and 475A.

My 2 cents,

Leo


bill koski
 

I suggest if you want to be real careful drilling to put the bit in a pin vise and drill by hand.


Jean-Paul
 

satbeginner, very fine, but risky in the packed construction of the SC502.

If one of the species multi section pots is damaged finding a new part and replacing would be horrible.

As each scope has many of them, the chances of breaking are multiplied

I was hoping for a less drastic solution.

Also advice on the best cleaner solution to use.

Bon journée

Jon


Dick
 

For Pots, use what the Pro's use. Caig Labs Fader Lube. Contact cleaner may
destroy the Pot.

Available on Amazon (what isn't !!).

73, Dick, W1KSZ
________________________________
From: TekScopes@groups.io <TekScopes@groups.io> on behalf of Jean-Paul <jonpaul@ix.netcom.com>
Sent: Monday, February 15, 2021 8:10 AM
To: TekScopes@groups.io <TekScopes@groups.io>
Subject: Re: [TekScopes] Cleaning Scratchy Bourns MOD pots

satbeginner, very fine, but risky in the packed construction of the SC502.

If one of the species multi section pots is damaged finding a new part and replacing would be horrible.

As each scope has many of them, the chances of breaking are multiplied

I was hoping for a less drastic solution.

Also advice on the best cleaner solution to use.

Bon journée

Jon


Ed Breya
 

A safer approach may be the more drastic measure of drilling out the rivets, then you can take it apart for full access. You can replace the rivets with long screws, about 2-56 here, or metric equivalent. I think these and the Allen-Bradley mod-pots (that are screwed together) have been discussed recently too. I just restored a single section A-B one recently - a bad level control on a Wavetek 3000, that was totally intermittent. I figured I could do it without unhooking from the wires, just long enough to get the pot accessible. I managed to get it apart and hit it with D100, right from the back of the rotor, which is the closest access to the resistance element. It went back together OK, but took quite a few rotations before it cleaned up and smoothed out. If you try to just spray cleaners from the outside or shaft bushing, it's a long trip to expect anything to soak in and reach the wiper and element. So, drilling a strategically located access hole, or disassembly are the "simple" ways to go. I think I've mentioned vacuum methods here too, recently, where you put suction on the pot and use that in various ways to pull lots of cleaner inside.

Ed


Jean-Paul
 

Hello again Ed and Dick, thanks for the tips.

One limitation in SC502 is the very tight layout, so each pot would need to be removed for the proceedures Ed suggests.

I am going to try IPA 99% and contact cleaner, and see if I can get any improvement.

If not, then I would consider more drastic measures.

Kind Regards,

Jon


Matt
 

Jon,

I have no experience with this, but it might work for some. Stewart MacDonald Guitar Shop Supply sells a special cap with a side hole designed to screw (3/8 x 32-thread) onto the shaft of a pot on an electric guitar. This is used in conjunction with a can of CAIG DeoxIT to get the DeoxIT to flow down the shaft of the pot and inside where it is needed.

See: https://www.stewmac.com/luthier-tools-and-supplies/tools-by-job/tools-for-maintenance/pot-cleaning-cap.html

I haven't seen this at work, and perhaps it is not applicable to your pots, but at $24, it might be worth a try.

Matt

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Jean-Paul
Sent: Monday, February 15, 2021 11:18 AM
To: TekScopes@groups.io
Subject: Re: [TekScopes] Cleaning Scratchy Bourns MOD pots

Hello again Ed and Dick, thanks for the tips.

One limitation in SC502 is the very tight layout, so each pot would need to be removed for the proceedures Ed suggests.

I am going to try IPA 99% and contact cleaner, and see if I can get any improvement.

If not, then I would consider more drastic measures.

Kind Regards,

Jon


Jean-Paul
 

Rebonjour a tous, many thanks for all the tips,

I shall put the Craig Labs Deoxit and Fader on order.

Meanwhile, I have fixed both SC 502,using the syringe with 99% IPA, and injecting at the shafts and each wafer joint.
The IPA and exercisingfixed all the scratchy controls.

Finally, I can only marvel at this TEK packaging and engineering design,
a fully capable 15 MHz 2 ch scope with all basic features and 1 mV per div VER, in a box only 5" x 5" x 10"

I am very happy that disassembly of this puzzle palace was not needed.

Bon journee,


Jon


Carl Hallberg
 

There is lubricant on/in the shaft and when spraying from the shaft end this will put lubricant plus some cleaner on the control surface and remove lubricant from the shaft.  Long term effects, I don't know.
Carl Hallberg (W9CJH)

On Monday, February 15, 2021, 10:38:32 AM CST, Matthew Hofmann <mhofmann@sbcglobal.net> wrote:





Jon,

I have no experience with this, but it might work for some.  Stewart MacDonald Guitar Shop Supply sells a special cap with a side hole designed to screw (3/8 x 32-thread) onto the shaft of a pot on an electric guitar.  This is used in conjunction with a can of CAIG DeoxIT to get the DeoxIT to flow down the shaft of the pot and inside where it is needed.

See: https://www.stewmac.com/luthier-tools-and-supplies/tools-by-job/tools-for-maintenance/pot-cleaning-cap.html

I haven't seen this at work, and perhaps it is not applicable to your pots, but at $24, it might be worth a try.

Matt


-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Jean-Paul
Sent: Monday, February 15, 2021 11:18 AM
To: TekScopes@groups.io
Subject: Re: [TekScopes] Cleaning Scratchy Bourns MOD pots

Hello again Ed and Dick, thanks for the tips.

One limitation in SC502 is the very tight layout, so each pot would need to be removed for the proceedures Ed suggests.

I am going to try IPA 99% and contact cleaner, and see if I can get any improvement.

If not, then I would consider more drastic measures.

Kind Regards,

Jon


Jared Cabot
 

For cleaning pots, I like to open them up an get inside if possible. The internal design of many of the pots that Tek uses makes it difficult and unlikely that cleaner applied down the shaft of the pot will ever make it to the resistance element or wiper, and basically impossible for multi-gang pots.
Some pots are sealed and glued which means you are pretty much out of luck (But so far, I have found those that are glued and totally sealed don't tend to get so scratchy, so far at least...), but many can be carefully opened for cleaning.

For example, the black Mod Pots often have flat head screws holding them together which makes them trivial to open.
Others like the blue Bourns pots for the front panel controls on the 24xx and 26xx series scopes have two pins holding them together. These only have two corners pinned, so you can push the pins out with a punch, clean the internals and then reinsert the pins into the diagonally opposite holes *carefully pushing them into place with some pliers) to close them up nice and tight again.
Other metal can types like for the CRT controls on the 24xx and 26xx series scopes can have the metal tabs carefully straightened to open them, then carefully crimped back closed afterwards.
When it comes to the riveted Clarostat pots or riveted Bourns pots, The rivets are usually plated brass or other soft metal, so a set of flush-sidecutters makes short work of cutting the tops off.
Then it's just a matter of using some appropriate length M1.4 or M1.6 (some Bourns pots have enough meat that they can be drilled out to M2 if needed) screws and nuts to close them back up.

As for cleaning, I like to give the resistance element a gentle wipe with isopropyl alcohol on a Kimwipe paper cloth, then use isopropyl alcohol on a small paintbrush to brush the wiper clean. Be careful with the carbon 'puck' style wiper in the Mod pots, it seems to be fixed in place on the wiper arm with conductive glue of some kind, but if you do knock it off, it isn't hard to carefully and sparingly solder it back in place.
After the pot is all cleaned and blown dry with some canned air, a wipe with a tiny bit Deoxit or Deoxit Fader depending how I feel at the time (I like to fill a few Hakko flux pens, part number FS210-82 with Deoxit for precision application) on the resistance element, followed by a little plastic-safe white silicon grease (You'll find this is commonly used in the Bourns pots) and it's all closed up again.

With a careful touch, I've never had a problem with rebuilding pots in multiple scopes and TM500 modules and other equipment, and the pots work excellently and feel great in use.


 

Hi Matt,
Thanks for yet another very interesting and clever technique that might work very well in some cases to fix noisy pots.
The only drawback I see with the little adapter Stewart McDonald makes is it is not tall (long) enough to allow for the many dual shaft pots that Tek uses on its instruments.
Fortunately it won't be hard to countersink and tap a 1 1/2" long piece of 3/8" diameter aluminum rod so it threads onto a 1/4" pot bushing. At the far end of the rod all it needs is a hole just large enough for the wand from an aerosol can of contact cleaner / lubricant to fit snugly into it.
It will even be easy to put a Luer Lock fitting on the other end so a syringe (or other devices) filled with contact cleaner can be dripped or forced into these pots / switches.
Dennis Tillman W7pF

--
Dennis Tillman
TekScopes Moderator


Dale H. Cook
 

On Mon, Feb 15, 2021 at 10:10 AM, Jean-Paul wrote:

Also advice on the best cleaner solution to use.
As one of the pros that Dick mentioned I will second him - use Caig FaderLube - it is designed for controls. Caig D-10 and G-10 are contact cleaners designed for cleaning switches, not controls.

Dale H. Cook, GR/HP/Tek Collector, Roanoke/Lynchburg, VA
https://plymouthcolony.net/starcity/radios/


 

Hi Ed,
I never thought about suction until you just mentioned it just now. Thank you for that intriguing new strategy for cleaning these sealed pots.

One idea I had (with no success) was to immerse the dual-pot/pull-switch assembly in cleaning solution in an ultrasonic cleaner. My hope was the ultrasonic bursting bubbles would be able to get some solution into the wipers through the shafts. I left the dual-pot/pull-switch assembly in the ultrasonic cleaner for a few hours to give it every chance to succeed. It had absolutely no effect :(

I did consider removing the rivets but decided against it since I was sure nobody sold 1 1/2" 2-56 screws. Reading your email made me realize that was a stupid assumption. McMaster-Carr sells 2-56 screws up to 1 3/4" long at very reasonable prices ($7 for 25 screws). There are even longer ones but they cost much more.

The particular dual-pot/pull-switch I desperately need to clean is the one that controls the output level and DC offset of an otherwise pristine late model FG 501A function generator. This is a very impressive plugin capable of 30Vp-p into 50 ohms from 0.2milliHz to several MHz. I would REALLY like to be able to adjust the DC offset (which goes from +15V to -15V) so I could set the square wave output to go from 0V to +30V into 50 ohms. That is more than 1/2A output!!!

My concern now is that if I remove ALL of the rivets I will have a very difficult time getting it all back together. Do you think I would be able to get cleaning solution into the assembly if I drilled out two of the rivets on opposite corners of the assembly?

I suppose if I was going to go that far it would be better to drill out one rivet at a time and replace it with a screw loosely tightened on the assembly. Once all 4 rivets were replaced with loosely tightened screws this way there should be sufficient room for cleaning solution to get in without altering the alignment and arrangement of the internal parts.

I think I just answered my own question. But once again I could not have done it without your help.
I'm ordering the 1/1/2" 2-56 screws I need from McMaster-Carr right now.

Thank you Ed!!!

Dennis

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Ed Breya via groups.io
Sent: Monday, February 15, 2021 8:06 AM
To: TekScopes@groups.io
Subject: Re: [TekScopes] Cleaning Scratchy Bourns MOD pots

A safer approach may be the more drastic measure of drilling out the rivets, then you can take it apart for full access. You can replace the rivets with long screws, about 2-56 here, or metric equivalent. I think these and the Allen-Bradley mod-pots (that are screwed together) have been discussed recently too. I just restored a single section A-B one recently - a bad level control on a Wavetek 3000, that was totally intermittent. I figured I could do it without unhooking from the wires, just long enough to get the pot accessible. I managed to get it apart and hit it with D100, right from the back of the rotor, which is the closest access to the resistance element. It went back together OK, but took quite a few rotations before it cleaned up and smoothed out. If you try to just spray cleaners from the outside or shaft bushing, it's a long trip to expect anything to soak in and reach the wiper and element. So, drilling a strategically located access hole, or disassembly are the "simple" ways to go. I think I've mentioned vacuum methods here too, recently, where you put suction on the pot and use that in various ways to pull lots of cleaner inside.

Ed







--
Dennis Tillman W7pF
TekScopes Moderator


-
 

Dennis,

Skycraft surplus store in Orlando has 2-56 and smaller screws. They
even have 0-80 screws in there. IIRC the price was about 10c each.

On Thu, Feb 18, 2021 at 7:01 PM Dennis Tillman W7pF <dennis@ridesoft.com>
wrote:

Hi Ed,
I never thought about suction until you just mentioned it just now. Thank
you for that intriguing new strategy for cleaning these sealed pots.

One idea I had (with no success) was to immerse the dual-pot/pull-switch
assembly in cleaning solution in an ultrasonic cleaner. My hope was the
ultrasonic bursting bubbles would be able to get some solution into the
wipers through the shafts. I left the dual-pot/pull-switch assembly in the
ultrasonic cleaner for a few hours to give it every chance to succeed. It
had absolutely no effect :(

I did consider removing the rivets but decided against it since I was sure
nobody sold 1 1/2" 2-56 screws. Reading your email made me realize that was
a stupid assumption. McMaster-Carr sells 2-56 screws up to 1 3/4" long at
very reasonable prices ($7 for 25 screws). There are even longer ones but
they cost much more.

The particular dual-pot/pull-switch I desperately need to clean is the one
that controls the output level and DC offset of an otherwise pristine late
model FG 501A function generator. This is a very impressive plugin capable
of 30Vp-p into 50 ohms from 0.2milliHz to several MHz. I would REALLY like
to be able to adjust the DC offset (which goes from +15V to -15V) so I
could set the square wave output to go from 0V to +30V into 50 ohms. That
is more than 1/2A output!!!

My concern now is that if I remove ALL of the rivets I will have a very
difficult time getting it all back together. Do you think I would be able
to get cleaning solution into the assembly if I drilled out two of the
rivets on opposite corners of the assembly?

I suppose if I was going to go that far it would be better to drill out
one rivet at a time and replace it with a screw loosely tightened on the
assembly. Once all 4 rivets were replaced with loosely tightened screws
this way there should be sufficient room for cleaning solution to get in
without altering the alignment and arrangement of the internal parts.

I think I just answered my own question. But once again I could not have
done it without your help.
I'm ordering the 1/1/2" 2-56 screws I need from McMaster-Carr right now.

Thank you Ed!!!

Dennis

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Ed
Breya via groups.io
Sent: Monday, February 15, 2021 8:06 AM
To: TekScopes@groups.io
Subject: Re: [TekScopes] Cleaning Scratchy Bourns MOD pots

A safer approach may be the more drastic measure of drilling out the
rivets, then you can take it apart for full access. You can replace the
rivets with long screws, about 2-56 here, or metric equivalent. I think
these and the Allen-Bradley mod-pots (that are screwed together) have been
discussed recently too. I just restored a single section A-B one recently -
a bad level control on a Wavetek 3000, that was totally intermittent. I
figured I could do it without unhooking from the wires, just long enough to
get the pot accessible. I managed to get it apart and hit it with D100,
right from the back of the rotor, which is the closest access to the
resistance element. It went back together OK, but took quite a few
rotations before it cleaned up and smoothed out. If you try to just spray
cleaners from the outside or shaft bushing, it's a long trip to expect
anything to soak in and reach the wiper and element. So, drilling a
strategically located access hole, or disassembly are the "simple" ways to
go. I think I've mentioned vacuum methods here too, recently, where you put
suction on the pot and use that in various ways to pull lots of cleaner
inside.

Ed







--
Dennis Tillman W7pF
TekScopes Moderator






Renée
 

Check at the hobby shops especially train and plane builders....I have obtained brass ones
Renée

On 2/18/21 4:06 PM, - wrote:
Dennis,

Skycraft surplus store in Orlando has 2-56 and smaller screws. They
even have 0-80 screws in there. IIRC the price was about 10c each.

On Thu, Feb 18, 2021 at 7:01 PM Dennis Tillman W7pF <dennis@ridesoft.com>
wrote:

Hi Ed,
I never thought about suction until you just mentioned it just now. Thank
you for that intriguing new strategy for cleaning these sealed pots.

One idea I had (with no success) was to immerse the dual-pot/pull-switch
assembly in cleaning solution in an ultrasonic cleaner. My hope was the
ultrasonic bursting bubbles would be able to get some solution into the
wipers through the shafts. I left the dual-pot/pull-switch assembly in the
ultrasonic cleaner for a few hours to give it every chance to succeed. It
had absolutely no effect :(

I did consider removing the rivets but decided against it since I was sure
nobody sold 1 1/2" 2-56 screws. Reading your email made me realize that was
a stupid assumption. McMaster-Carr sells 2-56 screws up to 1 3/4" long at
very reasonable prices ($7 for 25 screws). There are even longer ones but
they cost much more.

The particular dual-pot/pull-switch I desperately need to clean is the one
that controls the output level and DC offset of an otherwise pristine late
model FG 501A function generator. This is a very impressive plugin capable
of 30Vp-p into 50 ohms from 0.2milliHz to several MHz. I would REALLY like
to be able to adjust the DC offset (which goes from +15V to -15V) so I
could set the square wave output to go from 0V to +30V into 50 ohms. That
is more than 1/2A output!!!

My concern now is that if I remove ALL of the rivets I will have a very
difficult time getting it all back together. Do you think I would be able
to get cleaning solution into the assembly if I drilled out two of the
rivets on opposite corners of the assembly?

I suppose if I was going to go that far it would be better to drill out
one rivet at a time and replace it with a screw loosely tightened on the
assembly. Once all 4 rivets were replaced with loosely tightened screws
this way there should be sufficient room for cleaning solution to get in
without altering the alignment and arrangement of the internal parts.

I think I just answered my own question. But once again I could not have
done it without your help.
I'm ordering the 1/1/2" 2-56 screws I need from McMaster-Carr right now.

Thank you Ed!!!

Dennis

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Ed
Breya via groups.io
Sent: Monday, February 15, 2021 8:06 AM
To: TekScopes@groups.io
Subject: Re: [TekScopes] Cleaning Scratchy Bourns MOD pots

A safer approach may be the more drastic measure of drilling out the
rivets, then you can take it apart for full access. You can replace the
rivets with long screws, about 2-56 here, or metric equivalent. I think
these and the Allen-Bradley mod-pots (that are screwed together) have been
discussed recently too. I just restored a single section A-B one recently -
a bad level control on a Wavetek 3000, that was totally intermittent. I
figured I could do it without unhooking from the wires, just long enough to
get the pot accessible. I managed to get it apart and hit it with D100,
right from the back of the rotor, which is the closest access to the
resistance element. It went back together OK, but took quite a few
rotations before it cleaned up and smoothed out. If you try to just spray
cleaners from the outside or shaft bushing, it's a long trip to expect
anything to soak in and reach the wiper and element. So, drilling a
strategically located access hole, or disassembly are the "simple" ways to
go. I think I've mentioned vacuum methods here too, recently, where you put
suction on the pot and use that in various ways to pull lots of cleaner
inside.

Ed







--
Dennis Tillman W7pF
TekScopes Moderator







Ed Breya
 

Hi Dennis,

I don't recall how the Bourns pots look inside, but with the A-B ones, you almost can't go wrong. Once you figure out how they did the modular construction, you don't have to fear taking them apart and rebuilding - especially if you have others to salvage sub-parts from, even if they're not the in quite same arrangement. I've recently been building some multi-section A-B ones from a collection of others (most salvaged from Tek stuff), but have been stymied by not having quite the right items (special couplings) from single-section ones, to gang them together for multi-section use. If you're just doing a clean and rebuild, you don't have to worry about finding different pieces to modify them. The main thing is, don't break the original guts, and keep track of the them and the order of assembly. The screws or rivets to hold it all together are secondary.Actually, if worse comes to worse, you can use wire. I think #14 or #12 solid wire is close enough in diameter to fill the corner holes, and stout enough to just fold over and hold the assembly together quite securely. I've done that before, on a temporary basis - ugly, but functional.

Ed


Renée
 

do be careful on bending the wire as it may break out a corner, usually upon removal when putting in the correct/ more correct screw..do not ask how I know...but it was eons ago on another project long forgotten but the lesson remained.
Renée

On 2/18/21 11:22 PM, Ed Breya via groups.io wrote:
Hi Dennis,

I don't recall how the Bourns pots look inside, but with the A-B ones, you almost can't go wrong. Once you figure out how they did the modular construction, you don't have to fear taking them apart and rebuilding - especially if you have others to salvage sub-parts from, even if they're not the in quite same arrangement. I've recently been building some multi-section A-B ones from a collection of others (most salvaged from Tek stuff), but have been stymied by not having quite the right items (special couplings) from single-section ones, to gang them together for multi-section use. If you're just doing a clean and rebuild, you don't have to worry about finding different pieces to modify them. The main thing is, don't break the original guts, and keep track of the them and the order of assembly. The screws or rivets to hold it all together are secondary.Actually, if worse comes to worse, you can use wire. I think #14 or #12 solid wire is close enough in diameter to fill the corner holes, and stout enough to just fold over and hold the assembly together quite securely. I've done that before, on a temporary basis - ugly, but functional.

Ed




John Griessen
 

On 2/19/21 1:22 AM, Ed Breya via groups.io wrote:
I think #14 or #12 solid wire is close enough in diameter to fill the corner holes, and stout enough to just fold over and hold the assembly together quite securely. I've done that before, on a temporary basis - ugly, but functional.
I love it! I have lots of 12 AWG 14 AWG for tying, mini rivets occasionally, better than baling wire, and now for pots it will hold tight when folded over and clamped/crimped some. Temporary-permanent is becoming a thing...for me at age 63 I'm less and less perfectionist.


Michael A. Terrell
 

Dennis Tillman W7pF wrote:
Hi Ed,
I never thought about suction until you just mentioned it just now. Thank you for that intriguing new strategy for cleaning these sealed pots.

One idea I had (with no success) was to immerse the dual-pot/pull-switch assembly in cleaning solution in an ultrasonic cleaner. My hope was the ultrasonic bursting bubbles would be able to get some solution into the wipers through the shafts. I left the dual-pot/pull-switch assembly in the ultrasonic cleaner for a few hours to give it every chance to succeed. It had absolutely no effect :(

I did consider removing the rivets but decided against it since I was sure nobody sold 1 1/2" 2-56 screws. Reading your email made me realize that was a stupid assumption. McMaster-Carr sells 2-56 screws up to 1 3/4" long at very reasonable prices ($7 for 25 screws). There are even longer ones but they cost much more.

The particular dual-pot/pull-switch I desperately need to clean is the one that controls the output level and DC offset of an otherwise pristine late model FG 501A function generator. This is a very impressive plugin capable of 30Vp-p into 50 ohms from 0.2milliHz to several MHz. I would REALLY like to be able to adjust the DC offset (which goes from +15V to -15V) so I could set the square wave output to go from 0V to +30V into 50 ohms. That is more than 1/2A output!!!

My concern now is that if I remove ALL of the rivets I will have a very difficult time getting it all back together. Do you think I would be able to get cleaning solution into the assembly if I drilled out two of the rivets on opposite corners of the assembly?

I suppose if I was going to go that far it would be better to drill out one rivet at a time and replace it with a screw loosely tightened on the assembly. Once all 4 rivets were replaced with loosely tightened screws this way there should be sufficient room for cleaning solution to get in without altering the alignment and arrangement of the internal parts.

I think I just answered my own question. But once again I could not have done it without your help.
I'm ordering the 1/1/2" 2-56 screws I need from McMaster-Carr right now.

Microdyne used Accurate Screw Machine Company for electronics type hardware for our products. They have a very wide array of stock items, and can make special hardware for production runs. screws start on page 113. Some on the group my find it useful for items they build to sell and need quantities of oddball hardware. I have included a link to their catalog:

<https://dpk3n3gg92jwt.cloudfront.net/domains/asm/pdf/Accurate_Screw_Machine_Catalog.pdf>


Fastenal has them. I don't know about your area, but I have four branches near me or you can buy online. :

<https://www.fastenal.com/product/fasteners/screws/machine-screws/600059?categoryId=600059&level=3&isExpanded=true&Length=1-1/2%22&Dia/Thread%20Size=%232-56&showAll=Length&productFamilyId=21356>