On Bill Pasternak, WA6ITF's advice, I checked all the software setting that can affect the microphone circuitry for the Icom 746 Pro. Nothing was amiss, but it made me think about "radio = computer"
I find that a hard CPU reset is usually good procedure when things start failing. Sometimes it will fix it, sometimes it won't but it can never hurt to try. 73s John AA5JG ___________________________