In case this comes up for anyone else here's my situation. One day the radio works fine, the next no sound coming out of the speakers. I searched on here and determined it is most likely the factory amp. After digging through the back and removing the amp I find the electrical connector all corroded and oxidized. Puzzling enough is the area is not wet at all and looks to have never been. The amp seems to be mounted near a vent so I am assuming over time moisture has "seeped" in. But after a quick clean and scrub the sound has returned. So before buying a replacement amp pull it out first, perhaps it just needs a good cleaning.