The last few months my Fender Supersonic combo has been driving me nuts. It sounds as good as usual, but the reverb seems to make a slight clicking/put-put sound. I had no idea what might be going on, so I swapped out the tube reverb send/return tubes with some I had hanging around. This seems to have fixed it for a few days, but then it came back. I checked the reverb tank connection, and everything else I could think of, and after putting it all back together the problem was gone again. Then it came back. I just solved the problem. Turns out the reverb channel was picking up some electrical interference from my NAS server in the same room. The reverb only clicks when the hard drives are reading/writing, so I moved the NAS to a different wall socket/circuit and the problem went away. I can't believe I was stupid enough to not try the PLUG first.
Anyway, all is good again.
Anyway, all is good again.