Playmaster 40/40 amp

Way way back in 197x (Not sure of the exact year), I built a amp from (I assume) a Dick Smith kit.  This was a 40W RMS class AB amp as I recall.  It had turn table preamps.  Many years later, I re purposed the turn table pre amps to mic amps and wired them in so that the microphones could be used to talk or sing in the case of karaoke over then music selected by the input selection switch.  The mic volume controls are the two pots at the back of the amp (Top left of the photo).  At a later time the whole amp was as the fold back amp for the bush band.  Then it sat unused for a year or so in the church shed before someone found it and suggested it be used to drive the speakers in the meeting room at church.

Inside, some of the wires had been cut off the selector switch.  I assume I did that for some illogical reason.  There also seemed to be no wires providing an input to the power amplifier part of the board.

I soldered the wires back onto the selector switch and through to the volume pot and then to the circuit board. 

Powered it up.  No smoke -> for my non technical friends, that is good because once the smoke leaks out it stops working. Measured the output voltage with no speakers attached and that was only a few millivolts.  Connected a couple of speakers that I could afford to loose.  The risk being that the amp if faulty could send out a high and or DC voltage and burn out the speaker coil.  Youtube via a PC provided some a musical source. 

One channel was fine but the other is noticeably distorted. I swapped the speakers over and the fault stayed with the channel.  I swapped the input from the PC over and the fault stayed with the channel.  I cut off the connection where the mic amps are mixed in and the  fault remained. 

Conclusion - There is something wrong with one of the channels.  A component level issue.  I'm not really motivated to fix it right now.