Thank you this information and drawing. Much appreciated. I will use this to try and pin the issue down. Any idea why the 25 ohm 5 watt wire wound resister on the left front side of the amp gets so hot? the one on the right side does not.This is crude, but you should get the idea.
Power for the rear board travels through the small wire from the fuse holders, touching the protection diode, and then to the rear trace on the board. From there it goes through the wire with the chokes to the trace where the output transformer is soldered. Power then flows through the transformer to the other side where it is soldered to the traces that the collectors are soldered to. That is where the transistors get there power.
The blue circle is the diode, the green is the chokes, and red is the path of power.
If one had failed I think that would just cause the other fuse to pop from over current as the two holders are still connected to each other.I know this is obvious , but has the fuse holder failed?
I have seen them fail before, just check to see if power is getting through the fuses.
The fuse holders are tied together and feed both boards.The 5-Watt resistor gets hot because it has power applied to it when the relay is keyed. Texas Star scrimped on the size of that resistor. 5 Watts is almost big enough, IMHO. A 10-Watt resistor would not run as hot. Or be as cheap. The one in the rear stays cold because no power is reaching it.
The fuseholder for the back pair of transistors has a wire that leads down to the rear pc board. Take the meter probe and see that this wire has power, and then follow the foil trace where it's soldered and see how far down the probe still shows power present.
Really sounds like a damaged foil trace on the rear pc board.