There is nothing wrong with this amp, I love it, I am just purashed a GK 800rb. This amp is in very good condition with 2 newer JJ tesla 12ax7s. The only "problem" with this head, a common issue in the earlier heads was the dirty effects loop inputs. I sprayed contact cleaner in them both and run a patch cable through it and it works perfectly fine. Loud as hell!!! This amp is very loud, but I just bought a GK 800RB so this has to go! $450 shipped CONUS/Lower 48 only shoot me a pm!