Hello to all and thanx for any insight, instruction, and assistance in advance! I'll try and keep this short but add what info is prevalent... 199something svt-3pro, used it for rehearsal and gigs maybe 4 times a week for a good 3 years. then it went on a shelf, for at least 10 years. Hooked it up a year or so ago no sound, nada, didn't mess with it. This week got a new tungsol tubes, quad 12ax7, 12au7w. Biased the mosfets (matching groups(red dot rt side facing, green dots, left facing)) left side average 22.275mv right side average 21.9mv. Now back to my problem, I get almost no volume from the speaker cab 2x15(4ohm)unless Master Volume,Gain and Tube Gain knobs are MAXED out! Zero volume with Gain and Master maxed, only while adding tube gain does the volume come up. We're talking minimal volume, like barely a 2 on a scale of zero to what this amp can put out. The Peak light works as it comes on when i hit the mute button but with all knobs maxed it never flickers. 12ax and 12au seem to be glowing pretty good, front 12ax7's seem dimmer but lit. Cabinet, cables, etc are all good as proven by connecting my v4bh up and things are copacetic. I cant tell if any of the big caps are bad cuz they have a plastic cover of sorts on top. all smaller caps appear ok as i see no evidence bulging. I'm somewhat competent in electronics (biased without light show) but not in diagnostics. i can follow directions if someone can walk me thru it. So ....*** !!