I stole tremoverb combo from a pawn shop for $518 as the 2nd channel had no volume...
after swapping out the pre amp tubes to no avail, I ended up sending my Tremoverb chassis to Mesa Boogie in CA where they cleaned it up - replaced a pot that died - which they said was my main problem and they cleaned up the LDR upgrades which had actually been installed in my amp - but poorly done per Mike Bendelini who called me him self to give the doctor's report!
$125 later plus $40 shipping, I had the chassis back, reinstalled it into my combo and boom, I have a kick *** amp!
even though I have marshalls, I have never played through and amp that had so much overdrive that I didn't need a pedal as well!
G