I just picked up an old German plywood shop bass, and when I finally got it home, started to notice a buzz. It comes and goes, but when it's there it almost sounds like the bass is played through an overdrive pedal. I have spent the last two days reading bass bar horror stories, and I want to know what a bass bar problem sounds like. Apologies if this is a repeat thread, but I couldn't find this info anywhere. So far, when the buzz is there, it's on almost every note. The top is a little bit sunken in by the bridge, but from what I understand this is fairly typical of old plywood basses. It seems to be stable. When I place a finger inside and pull the top up (away from the back) the buzz seems to go away. I can't find any glaring seams, and it isn't long endpin buzz. Bass bar? Sound post? Any ideas?