Luxman 5M21 not working

Beautiful one owner amp. This was my uncle's. It was part of an all Luxman system and used to drive Snell A3s. Up to the point where is stopped working, it functioned flawlessly. (sound quality, back lit gauges, etc.) You must be within a matter of inches to see any scratches. Unit powers up. but the protection system will not let it come out of standby. It is seeing a DC offset. About 10 years ago, I took it for service at Alternative Audio in Lilburn, GA. They said that one of the differential ICs went bad and needed replaced. Said if I could locate one, they could replace it easily.
I've never gotten around to fixing this so now, time to pass along to someone who can take the time. The buyer would have three choices. 1. find another DC coupled Laboritory Reference Series piece that is not working and pull the IC from it. (this was used in all the Amps and Preamps of that series) 2. build the replacement from discrete components. (I have a schematic of the IC and the pin outs) or 3. gut the boards and use the chassis, transformers, etc to build a different amp.
Please contact me with questions.