If it's strictly a problem caused by loose inputs, then you should get it fixed fast before it messes something else up internally. The repair for something so basic shouldn't be too expensive. Most decent, local repair shops (maybe even some authorized by B&K) could probably do the work.
Problem with inputs
I just got a B&K AV2500 Series 1 amp to play with. Of course it was used. The input jacks on the back are lose and I'm getting a terrible squelch through my speakers. Every once in a while I can get it to work but not often. I thought it was a ground in my cables but I switched them out and gently flicked my cables and it squelched again. So it has to be the inputs that are loose. I tired to tighten them but the screw is stripped and it will only tight just a bit. Is there anyway I can fix this? Because the inputs are loose did the ground break? Any feedback would be great