I had a similar situation.? It turned out to be my mic jack was slightly loose at the case (the mounting screw was snug but not super tight).? When I plugged the mic in, I was inadvertently (and unknowingly) twisting the entire jack clockwise and it was shorting the mic wiring on the pins against the LCD display assembly.? To correct the problem I rotated the jack away from the short, tightened the mounting screw, and (for good measure) placed some electrical tape between the jack wiring and the LCD display assembly.? Not sure if this will work for you but it did the trick for me.
Tom
AB7WT
