I have an old Memory Craft 9000 that has worked beautifully since the early 1990’s. I’ve recently replaced the sewing functionality with an M7 and planned to keep the 9000 for embroidery for a few more years. 

Unfortunately I am now experiencing tension problems. I’ve cleaned everything and replaced the needle but continue to have tension issues, especially after the machine has run for 5+ minutes and is getting warm.  It appears that the thread (top) tension disks are not properly engaging.  The thread pulls through the tension disks with the same effort regardless of whether the pressure foot is up or down (sewing mode or embroidery mode).

Does anyone have suggestions or tricks to get this back working (aside from hoping that the dealer can fix such an old machine)?  

Despite popular belief, the Scan-n-sew PC with Ver 2 of the software is compatible with Windows 10. All that is required is a simple Serial to USB cable and a windows setting to map the serial port.  I am easily able to put downloaded designs onto the 9000 memory card and would love to get this machine working again. 

Thanks in advance for any help or suggestions 

It sounds like there may be debris lodged between the tension discs, so they cannot close properly. Take a strip of scrap fabric (Denim is especially good for this.), raise the presser foot, fold the scrap in half, and "floss" the tension with the folded edge. That will usually work out whatever is in there. Only once did I have to disassemble a machine to fix this problem. In that case the sticky "dot" from the label on the spool had ridden down the thread and attached it self to a disc. Good luck!

Thanks for such a quick response.
I did as you suggested and was able to clear out some dust and lint. Unfortunately the tension disks still do not appear to be engaging. 

I am fairly confident that there is no debris as I have removed the top cover and have visibility to the top/back of the tension disks. When I lower the presser foot, the right disk moves towards the other, but definitely doesn’t engage. I’ve adjusted the tension screw and see that affects the spacing but not enough to provide any tension.   I see that the gears for this mechanism are plastic or nylon.  Is it likely that they have worn out?  Do you have any idea if these parts would still be available?

thanks again.

Keep in mind that the tension is held open mechanically when the presser foot is up. With the top cover removed, put the foot down and turn the machine on. You'll see the tension adjusting gears move through their full rotation in the power-on self-test. It's very unlikely they have worn out, since the self-test runs them through the full range of motion. If they don't make it, you get an error. While you have that top cover off, notice the little cover on the top side with the dotted line showing the thread path. That cover is held on by a screw, which is removed from the bottom of the top cover. If you take it off you may find an accumulation of thread debris. Normally that will cause a dramatic increase in thread tension, not a decrease. Also, with top cover off and presser foot UP, shine a strong light over the tension discs. Use a long thin needle to probe between them. If something is stuck in there you should see it.

I had previously done most of what you suggested—removed top cover, used a bright light to view between the disks, visually check for debris.
You stated “You'll see the tension adjusting gears move through their full rotation in the power-on self-test.”  During that power on test, those gears by the tension mechanism do not move. The needle and the embroidery carriage both move and seemingly do a self check. Does this indicate a hardware issue?

Any more ideas?  After finding the schematic for this machine, I’ve started looking for parts.  If in fact I need a tension unit, it isn’t obviously available. Are there any secret sources for parts or shops that you know of that have a large parts stash?

It's been at least 15 years since I last worked on a 9000, so my memory might not be reliable regarding the self-test. However you may be able to verify operation another way. Again, with top cover off, foot down, sew a stitch or two. Then adjust the tension from the touch screen, going up and down. You should see a "twitch" in the gear each time you do that. If it doesn't, then the stepper motor is not being triggered. That could be the motor itself, but usually it's a driver transistor that goes out. You are correct about parts availability being a problem. Janome does not have a very deep stock on parts, and it's usually only complete assemblies - like the entire tension unit instead of just the stepping motor. The best hope would be to find a used machine that may or may not be working. The tension is not a likely source of trouble on the 9000, so if you could buy a "parts donor" cheaply it would likely have what you need. You could also use the schematic to follow the logic for the stepper motor back to the driver transistor. Those are not socketed, but with just 3 pins to unsolder, it might be replaceable with a lot of hassle. And if you take it out, you could maybe test it to confirm it was the issue before getting a new one. The stepper motor itself plugs into the F board, which is a small board that handles the buttons on the front panel. I don't remember whether there are parts on that board, or if it's just a collection point to take all the buttons and the motor to a single cable back to the A board, which is the main one.

Thank you for all of your help!  I’ll see how far I can take it from here. 

or maybe start a GoFundMe for a 550e (ha ha!)