Alright! Tube amp is really alive now. Looks like I had left out a wire connecting one of the preamp tubes to the circuit board. Why it worked half-assed the other day, I don't know. I seemed to have lost the clean tone though. It's either distorted and quiet or distorted and loud - not that there's anything wrong with that.
Would be nice to get the clean tones though.
Off to a farewell dinner for a friend. More playing when I get home.