The culprit on these one turned out to be a loose capacitor on the preamp board.

^ Yeah, that one. I removed without messing with the solder joints and you can see it easier.

All I had to do was solder it back and  shorten a couple of wires that had the leads too long. They were about to snap and they had the potential to short with the wires next to them. I put it all back together and that solved the problem.