[Elecraft] K3 doesn't receive at power up

[n0tt1 at juno.com]

Greetings from Missouri....

Guys...I have a K3 which has been very reliable for years, but now it
has a problem.  At "power-up" from a cold start, it
doesn't receive.  I do get audio.  It acts like no antenna
is connected.

If I power-down, then power-up again everything appears
to be normal, at least for awhile.  The power supply is okay.

Once, recently, when the radio was warm, I had a no-receive problem
that occured when I switched bands.  My P3 would display a "large" 
signal that would not tune.

Has anyone experienced similar problems and what generally was done
to repair it? 

Thanks,
Charlie, N0TT