Tom, Since this happens at odd times with long periods between events, I'm not sure I would start doing major changes "just in case". Fire up the radio and start jiggling coax connectors. Between radio and amp, amp to TW-1, and TW-1 to tuner. So there are 3 jumpers and 6 connectors to play with. I would check the voltage on the power supply, but I seem to remember that a few times over the years when you had a problem and suspected ps voltage, it always turned out to be something else. Bad jumper one time if I recall. If the problem returns, connect your dummy load or antenna direct to the radio, see if RX comes back and check swr using the Kenwood's VGS-1. I think sending it out for service at this point will just result in a "no problem found" reply as well as loss of radio time and shipping costs. You can always box it up and send it here, I'll be happy to evaluate it for a few months n/c. 73, Steve KW3A