HElP!!!!

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.
 
I just moved to a new city, unfortunately left most of my tools at home cause I wasn't expecting to be doing any projects in the short term. Just discovered that if I hold the amp vertically, on its side the channel comes back. Now using the speaker on/off switch works as normal. Must be a little friction or something in the solenoid that gravity helps?? Probably can keep it this way for the party, but not good long term.