So here's the story, I have a 333xl infinium that's my gig head. I have been looking for a Trirec infinium and found one used at a Guitar center near me. The problem is that it was traded in working but doesn't work now. It powers up, lights come on, channels switch, everything appears fine but there is only the faintest of sound from it. The only control that even changes this faint sound is the vari power knob. It was listed at $450 but "clearanced" at $339 not working. After talking to a manager they sId said I could buy it for $275. I'm not much of a gambler so I passed. It looks almost new, not even any scuffs on the foot pedal. Is there a common failure that causes this that is an easy fix? Bad ground, loose ribbon connector? I'm not sure how old it is . Will Behringer/ Bugera repair it ? Thanks for any advice.