Working on a friends M-80 that was re-capped and had the infamous glue completely cleaned and all local corroded components replaced. It was working fine until recently, when the left channel went out. First thing I did was unsolder all 8x output transistors to test out of circuit, all tested okay using diode test function on DMM. I also tested the other 8x power transistors on power boards 3 and 4, all tested okay. I also tested the driver transistors on the power boards, and the bias current transistors on the main board, all tested okay. Second thing I did was solder in 470 ohm 1/2 watt resistors across the bases and emitters of all output transistors per this awesome thread: http://audiokarma.org/forums/index....-if-you-are-servicing-a-yamaha-m80-85.591887/ I then powered on using a DBT with a 100 watt bulb, it powered on perfectly! The bulb dims and all is well. I tested base voltages at all output transistors, which measure around 1 volt with out any load. Collector voltages are +/- 39.5 volts. Thinking I was clear for takeoff, I re-soldered all output transistors, powered on DBT and the bulb shows a dead short. If I remove the RP/LP power wires, there is no short and it powers on fine. I also tried removing one power feed at a time, both channels show a short. Should of left the working channel alone, I regret that decision! Any idea on where to start? I've inspected my solder connections up and down under microscope, I've tested for shorts between the collectors and ground. Could my meter be giving me a false sense that the output transistors are okay? Thanks in advance for your help, here are a few pictures to reference!