A bit of potentially relevant history:
* for months now, out of nowhere, my right channel would occasionally pick up a bit of static, it just sounded like random white noise and existed independent of volume. the solution was to un/replug the headphones, after which it would either get louder or quieter or go away... I'd just keep replugging the headphones in until the static went away. it also would happen when turning the amp off, while the tubes cooled down. it was annoying but I had no idea what the issue was and I'm writing a dissertation now, so I just ignored it.
* recently, I replaced the volume control with a cheap stepped attenuator and replaced the signal wire from the RCA jacks to the new volume control.
I was listening to music last night, and decided that I wasn't feeling the tubes I was currently using. I turned the amp off, pulled the tubes, put some different tubes in, fired up the amp, and....no right channel. The first thing I tried was swapping back to the other tubes, but still no right channel. I tried checking the connections with the DAC and trying other amps, but everything else worked fine. I tried unplugging/replugging the headphones, but nothing. I tried jiggling the tubes, which got me a few pops in the right channel (notably loud from the 12AU7), but overall no success.
My first assumption was that I'd done something wrong adding the new attenuator (despite it having worked for ~2 weeks prior), but using my DMM the signal path into and out of the attenuator as far as the 12AU7 inputs was perfectly intact. The output stage (modded with film caps) seems to be clear as well.
My suspicion now is that something is wrong with the 12AU7 socket, specifically the 'right channel in' pin. While putting in the new attenuator, the wire from the attenuator right channel out to 12AU7 right channel in was a bit short, however I didn't want to have to unscrew the Speedball boards and move them (lazy, I know) to replace it, and besides it looked like it might be just long enough. Upon inspection last night, the right channel input tab seemed bent inwards and a bit more loose than some others. The connection into the tab seems ok, but I don't know exactly how to check whether or not it's passing its signal along because the wiring gets a little tight and confusing.
Am I on the right path with my suspicion about the 12AU7 socket? It seems reasonable that the combination of being stretched along with too many tube rolls could have done something there. It also seems to me that, because there's a loud deep pop coming from rolling the 12AU7 tube around that something of the signal is getting through the 6080 and out to the headphones. On the other hand, this could be related to the static that I was hearing before, the source of which is still unknown. Any help you could provide in troubleshooting this issue would be greatly appreciated.
