Speakers used to work but now have worked only once for about 10 min. in the last 3 mos. . Can hear speaker relay clicking under dashboard when unit is turned on, but no sound from the front spkrs.

Could be you blew the front speakers. If the front speakers are factory, and you have a high power aftermarket stereo, it's very possible you smoked them. Try connecting a known good speaker to one of the front speaker terminals, and you'll know if the speakers are any good.