One of the channels on this amplifier is misbehaving . When there is a loud low frequency sound, the sound becomes distorted., returning to normal after a few seconds. Since this uses V Fet semiconductors, I believe that there is a defective coupling capacitor an open gate resistor or a defective Fet (hard to get since this amp is more then
20 years old. Hard to troubleshoot since I don't have a schematic. Any suggestions ?Vlad