Sony CDP-C79ES strange behavior

Hello All ANers, I'm a newbie, seeking advice. My system consists of (all Sony): STR-DA4ES Receiver, TC-WA9ES cassette deck, BDP-S1000ES blu-ray player, BDP-S350 blu-ray player, CD-RW33 CD burner, PCM-R300 DAT deck, CDP-C79ES CD 5 disc changer, LDP-600 LD player, SLV-998HF VCR, KV-32XBR6, KV-32XBR9, KV-32HS510 televisions, WM-D6C portable cassette deck, TCD-D8 portable DAT deck, ECM-929LT microphone. Now, on to the non-Sony gear: Four TrippLite suppressors, (7) JBL S26II speakers, (2) Infinity SM120 tower speakers, Energy EPS-150 subwoofer, Yamaha YST-SW200 subwoofer. Cabling is a mix of everything from Esoteric Audio, Parts-Express house brand, Belkin (high MSRP but bought on factory buy-out deals). I'm sure all of above pales in comparison to what some of you true audiophiles have spent over the years. On to my quandry: The C79 ES is really malfunctioning badly. The deck was bought in 1993 and has had medium use. Approx. 3 months ago I pushed the power button in, (the deck had been sitting w/o any use for 2 months or so), and nothing happened.I toggled the switch numerous times, nothing. I left the switch depressed and went about my business, to come back 3 hours or so later and find the unit on.So I left the power button depressed for several days, wondering if Sony used something akin to the CMOS batteries that were used in the x86 families of PCs. It was not a fix, to be sure. Even if you leave it powered up constantly now, only a few features work like Skip Disc, but you can not play a disc.It is such a beautiful unit (on board DSP, built like a tank, I would hate to let it go). I don't suppose anyone has had similar problems and found a solution? Any thoughts would be greatly appreciated, jm1976