I've just finished restoring Accuphase E202 with faulty stereo carbon volume control. When I removed the volume control, I made a series of measurements of resistance per particular rotor position and ch1 vs. ch2 was showing differences from several upto 8KOhms. Also measured the point where rotor position presumed to have same and balanced resistance and the angle between the rotors was almost 90deg. The volume control had an interesting structure and was connected in-series with balance control. Both potentiometers(volume and balance) are 250K. Wires from phonostage are connected to 50KOhm portion of carbon surface so that volume angle will be in sync with line level components.
It was a hard struggle to find matching remote control, but instead I purchased the Alps that had sufficient enough shaft length. The size of leads were unbelievably small and it was quite hassle to put all wires back together in place of substantially better built quality vintage one. I wanted to strip similar built volume from Fisher receiver, but owner changed his mind and now paying me to restore this one too. I didn't want to do any 'surgery' to the new volume control in order to divide it onto 50Kohm portions for phonostage so that the phonostage actually picks up volume from 10...11 O'clock and onwards.
Specialized high-end repair shop would quote $450 restoration job + another $200 for fixing the balance problem. They were insisting with '100% sure' attitude that it's not fault of volume control. When techies speaking to you, they assume that you don't even know the Ohm's law. When I started to argue with technical knowlege and experience, I didn't feel that they even belong to this business. I may only assume that I spoke to the techie that only knows how to intake the job, replace things, but has no idea how to diagnose.
Visualizing the components and circuit of Accuphase that I've restored, I can easily explain how the volume is being adjusted with balance. Balance adds a resistance to one channel or another making the voltage drop higher on one channel vs. another and the volume control makes resistance higher or lower to both channels at a time. The bottom line is that the higher the voltage drop accross potentiometer the lower signal you get so I would highly highly doubt that you can mount 50K volume pot instead of 250K.
I'm leaving electronic repair tech of stage sound and studio equipment including electronic musical instruments, amps, processors and pedals. Occasionally providing restoration of vintage audio and repairs for small audio dealers if I have time or need more money:-)