[Elecraft] K2 -- Erratic behaviour. Display changes and locks up

[C WEAVING]

I am a new owner of an early K2  with Seriel No 638. Initialy rig worked fine, but now a random fault is occuring . 
   
  I hear a couple of relay clicks (sometimes more) and the display rapidly changes and when stops,  the message  E137 0.26  or E138 0.26 is usualy given. On one occasion the display was left with St L 071. On other occasionns the display just appears random. Are these error codes, and if so could anyone give me their meaning.  The push buttons are non-functional and I can only get back to operation by switching OFF , and then ON.
   
  To me,  the symptoms are similar to my early computer experiences, when the computer went south.  Any recommendations for trouble shooting would be appreciated.
   
  The last point is that the problem is chronic during warm up. After 15 to 20 mins the problem is either gone or significantly reduced in magnitude.
   
  Thank you, Colin M3WCK