I built my 41hz AMP 5 a couple years ago now, just today it seems to have developed a problem with one of the left channel. It appears the solenoid is not connecting the channel, because there is no sound whatsoever. If I flip the on/off speaker switch a bunch of times it occasionally comes back, but then it gives out again soon after. Help!!! I've got a party tonight and I promised people good music, and I don't have a backup amp.