It sounds like the gain potentiometer is possibly damaged and might need to be replaced. You can find information on the pinout and part numbers of the potentiometers here: Are pisound circuit designs available? - #5 by Giedrius
It sounds like the gain potentiometer is possibly damaged and might need to be replaced. You can find information on the pinout and part numbers of the potentiometers here: Are pisound circuit designs available? - #5 by Giedrius