i own a late 70’s Blackface Dirt Road Special and i’m trying to solve a problem i’m having with it currently. The amp and built in Small Stone still work great. Only when i adjust the volume knob on the guitar, the amp makes the sound of a dirty pot turning. Regardless of the instrument used, i’ve tried many guitars, single and humbuckers, all with the same result. Its currently in the repair shop and after a thorough inspection of the board, it remains a mystery. I was hoping to get some advice from possibly someone who has better knowledge of the circuit, or just someone familiar with this issue on solid state amps?

Thanks