I’m pretty sure Solo will have those.

 

Those one at Solo ? ; Shop Marshall AVT Silver Knobs - Pkg of 8 Online

 

These are for round shaft not "D'" shaft.
If OP can make shaft round, it will fit.

Marshall AVT knobs ;

View attachment 617826

The set screw makes me think it would work.

 

The set screw makes me think it would work.

Nothing is certain, far from it. Even very little chance.
Have you ever tried it on a “D” shaft? I have.

 

I’m only trying to help OP, not looking for an argument here. Set screws are typically used on solid shaft pots. D or otherwise.

 

You must be able to align the mark (the black line) on the shaft in the correct position.
I would agree with you if there were no need to align a mark.

Here is a drawing that will help to better understand the problem, I hope.
If the set screw is on the round part of the shaft, it should be fine.

Who can tell where the set screw will be positioned before purchase of a knob ?

 

We haven't heard back from Bob Hosaluk about our suggestions after all, it's his amplifier that's involved.

 

 

Right , answer #5