Help needed to daignose amp problem(s)

[montesada]

Hi, this is my first post here, so be gentle!
I just bought an '81 Sunn Beta Lead combo. It works pretty good on Channel A but not on B.  The reverb knobs don't seem to do anything except on the B channel where when turning it, you go from almost no sound to a little, scratchy sound.
Also, the master volume doesn't work properly. No noise, but it works backwards from the numbers on the (obviously original) knob, and "0" doesn't shut it off completely.
My friend bypassed the master volume by using the plugs on the back and the volume of the clean sound (without drive) came way up, so the master volume pot is suspect, I guess?
I guess the B channel is blown and the reverb pan is too, but if I can get the A channel working properly I'll be pretty happy. The rest would be GRAVY. Any ideas?

[mckinnon audio]

  Hi there,sounds like someone replaced the master vol.control with the wrong value,and somehow wired it backwards.The reverb prob.might be the springs in the tank,sometimes they get stretched or broken and it'll sound pretty weird if they're touching each other or the tank.Don't give up on it,there's prob.some bad solder connections in the preamps that's why one isn't working,typical problems for older solid state gear.Hope this is of some help.good luck Mel.

[montesada]

Thanks for the help. It was my first instinct that it's fairly minor problems.
I went jammin' with it tonight and the other players were complementing the amp, big time. I still have to play with it and find some favorite settings, it's a bit of a challenge because the knobs change things so much, but I found a nice crunchy sound with my pedals and a nice clean sound. I also cranked it up a bit with the bass turned up and it almost knocked me over when I hit an Em chord. It DID knock some sheet music off the music stand in front of it! It was like a nuclear explosion, but clean. Wow, this thing has potential.