Hello, I have a Fender 94' Twin Amp, and the other week at practise, I was using the clean gain channel, when suddenly a huge volume increase just burst out, which is very odd, but when you switch to the drive channel, a loud feedback just rings out, no matter what you do to the volume control. The clean works ok, there seems to be some noise, but if you turn some controls past 4/5 it feedbacks. It has been at the music shop for some time, but the tech hasn't been able to find the problem, and this guy knows what he is doing, he has tried replacing a lot of components, but nothing changes. He emailed Fender, all they could do was guess really, they don't have a clue. I'm just wondering if anyone has come across this before? It's my main amp, so I'd like to get it back asap, but this has baffled everyone.