[Elecraft] K2 stoppages

[bfhawkins]

My K2 dies unexpectedly. Everything goes along fine then suddenly there is 
no output, and no recieve. I performed the following experiment:

Set the output at 10 watts.
Select the 80 meter band.
Connect the output of the ATU to a dummy load.
Connect the key input to the dit paddle.

I let the dits fly for about 15 minutes and the rig stops. No output,
although the sidetone continues to work. There is no indication of power on
the display, and the receiver has stopped working. I open the dit paddle and
turn the rig off. After a few seconds I turn the rig back on and everything
is OK again. I repeat the experiment on 40 meters and get the same result.

Where should I be looking for the problem?

73 de Ben Hawkins