Trident 80 question

[the shadow]

I've been working on a Trident 80 series(original 80 series NOT B or C) input module that has a mute problem. The mute light flickers then stays on when the board is powered up and it won't pass audio. It's acting as if another module is solo'd. I have practically rebuilt this module and now I have run out of things to try.Everything in the solo and mute logic circuits has been tested or replaced. If anyone has any ideas I'd be eternally grateful. Also if anyone knows of an extender board for sale or a source for the 32 pin connectors let me know.
Thanks

NOTE-I also posted this on Pro Sound Web. So if it looks familiar...