I have an old (80's?) Carlsbro Stingray Pro Bass head which I keep in my band's rehearsal room. After about 5 minutes of playing I start getting static-like noises and then the volume fades out to nothing. If I switch the amp off then on the volume comes back, but then the problem repeats. I've checked the cab, by using it with another amp and it's ok. I'm 100% certain it's not a problem with my leads. I do however think it's a problem with the power amp section of the amp, as I can connect the amp's pre-amp output up to another amp, and again it works fine. I was wondering whether I needed to replace the capacitors in the power amp stage. The amp is solid-state. Ideas anyone?