>>Does this happen to be the knobby you seek?
>Unfortunately, it isn't.
>The correct knob does not have the black insert at the front. Instead, there's empty space in that area to >allow the pull-out variable attenuation button with its white ring to "sink in" at least 5 mm, probably more like >7-8 mm.
>The knob on Ebay looks like what's used on e.g. the 1481 Waveform Monitor's front, at the right side.
Well that's a bummer.
I wonder if it's just a variation of the same knob, or if there is some other difference such as the shaft diameter..
If the only difference is the black plastic insert... well..
If I was the person needing that knob, I would buy this one and cut the black insert out.
The only problem is that I would have to physically have the knob in order to make sure that it'll fit the 7A13 in the first place.
Maybe the seller wouldn't mind breaking out a caliper and taking some measurements, though...?
*Actually, this knob appears to be the very same knob that is used on the 454 for V/div control. If it is, I have ones on my 454A that I could measure so we'll know if it's the same apart from the insert*
Making ones own replacement knobs may well end up being a very useful project for many people, though. Tek replacement knobs are bound to disappear at some point.
A database of replacement knobs would be useful... then part B of that database project could be adding 3D scans of good knobs so people can print off or machine replacements.