I came across a near mint '77 EH Talking Pedal--and it wants to work--but as you pedal thru the effect--it sounds like its shorting out (as the dual gang pot is turned--it's cutting in and out. Any chance it's anything other than the pot? Any hope of finding a replacement pot? The dual pots are totally enclosed--so I can't clean it. Could one disassemble the pot and clean it?