Let me start by saying I once had an Acoustic 360 that intermittently crapped out (sound would stop and come back). I had always suspected it was due to deep bass vibrations. I took it to 3 different amp techs and after paying their pound of flesh, I would get it back and still have the same problems everytime I turned up. Very frustrating because it was 50 miles back to the repairman and none of them could figure out the real problem I contacted the designer (Harvey Gurst), the wonders of the net, and he suggested I go into the preamp and tap on the transistors to see if I could find the problem. No luck but, I had to unassemble the amp frame during this process and found every point of contact had "black" corrosion. After cleaning all the frame connections with 300 grit sandpaper, and reassembling, the amp worked like brand new. 20 plus years I suffered with this problem and it turned out to be something so easy to fix. So.....my question is, have any of you had a long time nagging problem with your amp that turned out to be a very easy fix? Please describe?