So I have a Markbass CMD121P that I had to send away to Real Electronics just over a year ago. It’d starting dropping in volume, then coming back, and some farty popping and banging every now and then.    Sent it off to Real, they said there was nothing wrong with it but they replaced all the pots anyway and charged me £180 for the privilege. But miffed but assumed they knew what they were talking about.    Anyway, the gremlins are back. Some problems as before - sudden drops in vo