Sucks to hear that two of you are having dramatic hum issues.
Hope to hear more about what resolves the issue.
One thing worth trying - if your amp has the 'ext in' jack. Pulling tubes is a basic, useful test. Pulling the PI and getting no hum isn't super clear to me. But if you can isolate things by disconnecting everything before the ext in, and input a 'signal' at the ext in point (even if one that's silent, as with out a volume control, it's pretty loud to play anything at the ext in!), without the prior preamp stage also feeding the point, for the early amp schematics, that means you're down to one tube stage, the PI, power supply/filter caps, and the power amp stages as being part of the hum.
Having replaced all the coupling and filter caps puts you in good position -- it's what this amp needs regardless. Once you can get it running cleanly without so much hum, you'll be happy you did all that, for sure. Also sets you up for knowing the amp inside and out, which is useful down the road.
Sorry I can offer more help. Do you have a 'scope to get a handle on just how much hum you're getting, peak to peak, at various points in the audio circuit, and in the filtering circuit?
Hope to hear more about what resolves the issue.
One thing worth trying - if your amp has the 'ext in' jack. Pulling tubes is a basic, useful test. Pulling the PI and getting no hum isn't super clear to me. But if you can isolate things by disconnecting everything before the ext in, and input a 'signal' at the ext in point (even if one that's silent, as with out a volume control, it's pretty loud to play anything at the ext in!), without the prior preamp stage also feeding the point, for the early amp schematics, that means you're down to one tube stage, the PI, power supply/filter caps, and the power amp stages as being part of the hum.
Having replaced all the coupling and filter caps puts you in good position -- it's what this amp needs regardless. Once you can get it running cleanly without so much hum, you'll be happy you did all that, for sure. Also sets you up for knowing the amp inside and out, which is useful down the road.
Sorry I can offer more help. Do you have a 'scope to get a handle on just how much hum you're getting, peak to peak, at various points in the audio circuit, and in the filtering circuit?