I also would think shorted outputs if I got full constant rail on the output. It varies between +40 to +55 volts, the rail voltage is +78. At first, the offset is lower, 4-6 vdc, then, sometimes, the affected channel works fine. I'm thinking diff amp problem. Also, the POWER led doesn't light.
I'll certainly thank you to email me a schematic, board layout would be nice, too.
We were at one time your authorized service center here, but we had a bad manager who blew that for us.