K2 I/O problem

[SM0YQC]

I have used my K2 with HamRadio Deluxe for some time now.
Yesterday HRD said: 'Failed to read frequency'.

With HyperTerminal I can receive messages like FA3750000
but the K2 will not change frequncy wile sending SW01;

Every year with the first snow I got I/O or SWR-bridge problem.

So, where do I look first? Please advise.

Best 73's,
Rolf
SM0YQC
K2 #4979