Pioneer Elite M90 Woes

Hello -

As the title says, I've got an M90 that I'm working on that is riddled with problems. Aside from the numerous Omron relays with pitted contacts, the protection circuit is tempermental. I was able to succesfully burnish the contacts in all but one relay - the one that switches rail voltages for the lef channel. That one will have to be replaced. I'm betting this is common fare for these amps.

Specifically, the protection light remains on for an extended period of time after turning the amplifier on. In some cases, the circuit will disable, the selected speaker relay will close and you're off to the races. In most cases, it just stays in protect. I have a service manual for an M91, but it would seem that the two have different protection circuits.

This circuit is such that 12 VDC is the constant and ground is switched to power the relays. I have the 12 volts, but have been unable to trace back the problem with the ground side of the circuit. No DC is present at the speaker relays.

Any help that could offered would be greatly appreciated as I'd like to get this nice amp up and running.

Thanks!
Tony