I have a countryman b6 mic that i use with a sennheiser wireless g3 system. I am getting a little background hiss that i never noticed before. it goes away if i unplug the mic from the transmitter but leave the transmitter on. Not sure if it's still transmitting or not. But i noticed that on the plug of the mic itself, there is some kind of black discoloration. I tried to rub it off but i'm not sure of a good way to clean it. I'm surprised that such an expensive mic wouldn't have a gold plated terminal