My friends '57 Strat',after decades of happy playing, developed a nasty buzz about six months ago. At this time, no changes were made. I suspect failing solder connections. I didn't see any broken solder joints, but lots of lumpy amateurish work. Changing amps, cords doesn't help. It's been hard getting details from my friend, because, bless his heart, he's a guitarist. (30 years playing, and he looks at me blankly, when I mention neck relief.) The details 1957 Stratocaster Modded circa 1970 by Roger Linn unshielded No Fender electronics whatsoever. Gibson micro humbuckers Roger Linn pre-amp. (on a odd triangular piece of prototype board) Bridge, pots, jack shield, pups, are all grounded together; continuity is fine all over. Perhaps I missed something. I suspect a poor solder joint, that has continuity, but high resistance. Any ideas appreciated; TIA.