[Elecraft] Elecraft] K1-4 dead on 14MHz only

[Curt]

My K1-4, s/n 02258, built for 40,30,20&15  worked for 9 mos, until today. 
Now there is no output, no signal received on 20 meters.  The K1 functions 
fine in every respect on 40,30,&15 bands.  I noticed last few days that the 
audio on 20 was sometimes weaker than usual.  20 meters is open here, 
another transceiver used with same antenna system works fine.  .

I notice this is a relatively common problem, but have never seen any 
resolution for others ( like a. yoshida) who experienced the same 
difficulty.  He mentioned replacing the crystal which fixed the problem for 
4 days.

Suggestions?

Curt, KB5JO