This weekend when using one of my VHF's the guys I was running with said it sounded like I was talking underwater - the other radio was transmitting fine.

is there any test I can do on that mic to see if it has taken a dump on me or sould I just order a replacement?

Dont want to replace a radio if I do not have to. Would antenna issues cause that garbled transmission problem?

I think that one is an ICOM radio - the one that is working OK is a Stazndard Horizon so the mic's would not swap out.