Jim,
Thanks for the quick follow up. A few minutes after I sent my post of woe, I went back to the trunk. There are a handful of connectors for the phone's ECU, all of which I pulled. Two or three of the pins were heavily corroded, including a black wire pin.
Next step, into the drivers seat, powered up the car, turned on the stereo and ... nothing.
I scratched my head, wondered if I needed to either ground or 'unground' a wire. Got a bug up my butt, and pulled fuse #15 (radio 2). I'd already checked it yesterday, but hoped it was burnt. No luck.
I restored the fuse, turned the car on, and just about blew the doors off the car in the driveway next to me.
I now have a perfectly working Nakamichi stereo. All functions, tape, FM/AM, and CD work fine.
I suspect pulling the fuse and replacing it reset the 'Mute' status on the head unit. I did not connect any of the male/female clips in the ECU to each other. Just left them hanging. I'll give the lot a proper burial tomorrow.
Hopefully this info will help others with a similar issue.
Marty from Muggy, boiling, rainy, wonderful Palm Beach, Florida!