If you are not able to find a dual 120k volume control with centre taps for loudness you think about availability of a 100k one. I have a Technics amplifier that uses that value and I have a service manual that shows the loudness circuit.
You have not mentioned the brand and model number of your amplifier - it would interesting to see if there is a service manual and whether or not this is similar to the Technics version.
Here’s the one I found that I had ordered for one of my tube amps and never used II just removed it from the bag for these pics
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It would be a very difficult cut without removing the 8-leg pot from the PCB or some elaborate custom tooling. Also metal-dust in a pot is not a good idea.
I admit I don't have any good idea. In desperation I might try drilling a 1/8" hole in the stub, epoxying a 1/8" rod (without getting any slop on bushing!!), and drilling the busted-off piece or a replacement 1/8" and joining with 1/8"ID rubber fuel hose. But it is likely not going to be straight, and I don't know if everything will fit.
I HAVE lived with a busted-off stub on a pan-pot. There was enough fracture sticking out that I could put my thumb on the butt and turn it. It was an 8-ch mixer so I assigned some input which did not need pan to that channel.
I admit I don't have any good idea. In desperation I might try drilling a 1/8" hole in the stub, epoxying a 1/8" rod (without getting any slop on bushing!!), and drilling the busted-off piece or a replacement 1/8" and joining with 1/8"ID rubber fuel hose. But it is likely not going to be straight, and I don't know if everything will fit.
I HAVE lived with a busted-off stub on a pan-pot. There was enough fracture sticking out that I could put my thumb on the butt and turn it. It was an 8-ch mixer so I assigned some input which did not need pan to that channel.
OK, I would use a 100 kOhm Alps Blue and mount it on a bracket. There are no substitutes for this potentiometer model. You won't have the loudness stuff anymore. A member here sells remote controlled replacement potentiometers with MUSE attenuation. These probably can be made to fit too.