I've just bought a JCM900 second hand. For some reason, after I've played through it for a while, the volume starts to fluxuate like someone turning the knob up and down repeatedly. I turn the amp off, switch it back on and its ok again.
Also, whenever I use the channel switch pedal, it sometimes makes the controls from channel B work on channel A (never happens if I just press the button on the amp) and it completely cuts out the reverb in both channels.
Any ideas? I've got a gig coming up and I'm a bit stuck! :(
