One problem I came across when fixing these radios is usually what happens is the bulb does not make good contact with the circuitboard because of dust getting getting between the bulb ears and the cups. The cups get hot and melts the solder on the board. Im trying to find a replacement board on line but havent been able to find one. I am going to try to get one from AC Delco but they dont like to sell parts unless you are a qualified dealer. I dont know why because its my radio. And Im going to take it to an electronics store to see if they can fix it.
