[Elecraft] K2/100 Shuts Power Down

[Patrick DalPorto]

The K2/100 has been working very well for a couple of years but it has developed a problem.  I was on 15 m. SSB and made a quick call and the rig made a noise, shut down, and restarted.  It had shifted frequency and the fan was running when it came back on.  I readusted the tPA.  When I try to tune the radio at low power it tunes but will shut down very shortly.  
I thought I may have a bad diode in the SWR bridge but D16 and D17 seem to be fine when checked in the circuit.  Is it necessary to remove them from the circuit board to check them properly?

Anyone have any clues where I can start looking for the trouble.  I have put the low power top and tuner back on the rig and it works just fine.  I also tried the KAT100 and another tuner and the result is the same.

73,
Pat W8FV/5H9PD