After a what I thought was a successful restoration of a poorly 8080 it functioned perfectly for a few hours of tape playback and then threw a wobbly I cannot diagnose.
When you press play, you get extremely loud feedback from the left channel (the VU needle kicks wildly over to show this), the feedback subsides to a low noise leaving that channel at a lower output level than that coming from the right (and with some background feedback on the left channel). I have rebelted it (twice as one was misshapen), cleaned the mechanism, cleaned and lubed the record bar and switches, checked and rechecked the seating of the tape within the door and push on wire connections throughout the box.
The weird thing is, if I swap the playback selector to mono the feedback goes away and the channels return to what I would say is normal balanced playback.
Any suggestions gratefully received as I cant move on to the next box, until this one is done and its taken toooooo long.