Little more info, in case anyone out there has more experience with this stuff than I (which is to say, any at all) and would like to help.
Power up on the thing (when working) is accompanied by an initial, mechanical-sounding, click, followed a couple of seconds later by another one. The intial one appears to emanate from the vicinity of a roughly 1 x 1 inch box screwed to the board in the circuit path that appears to be directly between the power cord coming in and the transformer/power supply. I'm assuming it has to be some sort of soft-start circuit or manifestation of the actual power switch on the front of the box? The second click comes from roghly the other side of the chasis near the speaker taps.
Reason for the painful discription is, when this thing spontaneously shuts on and off, it's because that first clicking box just clicks on its own. It is extremely motion sensitive. Once on, a slight tap on it would cause it to shut down. (When I say shut down, I mean the unit looses power completely. Normally, when "off" there is a standby type light indicating that the unit is receiving power. Anger the little box, you loose everything.). If you tilt the unit at all, it would turn back on again. Maddening.
Anyway, I tried this for a while last night, until it just stopped turning on at all any more. Now it seems to be all the way dead, not just mostly.
SO, it appears that I'm going to need professional help on this one, but, just for curiosity's sake, what the hell is that box? Balck on the sides, brownish on top, and there's a rectangular little "window," for lack of a better word, on one half of the top with what appears to be a coil of wire coated in a green plastic sheath stuffed inside. Clearly, I don't have a clue, but I'm getting closer....?