In case anyone else has a similar issue...
My ICOM M34 handheld got to where it would only pick up one weather channel, and then only if squelch was turned all the way off. It didn't seem to send or receive on any of the regular channels. This was pretty much an all-of-a-sudden thing.
Thought it was toast, but I sent it to the ICOM service center in South Carolina and within 5 days, I had it back, with a new filter installed. It's long out of warranty, but this filter is a problem they know about, and they replace them for free.
Works great again, and all it cost was postage one way.