My Peavey Ultra 410 just started crackling and fading in and out (kinda hard to describe) but while I was playing it just started to fade out and then it came back for a second and just kept going that while I was playing, so I turned it off haven't really tried to fiddle with it at all. I know enough about electronics and amps to where if I was able to narrow down what the problem was I could fix it myself, otherwise I'll have to take it in to get it serviced, which isn't a bad idea, but I've only had the amp since Feb 2009, so it's not event hat old. Any advice? I think it's probably the fuse and/or something having to do with the preamp tubes.
It most likely to be the output valves. My amp does the same thing on and off, depending on the volume and the settings, but i haven't got round changing the valves yet.