[Elecraft] Strange K-3 Behavior in TX Data mode

[Pete Smith N4ZR]

Suddenly this morning, my K-3 is behaving strangely with WSJT-X.  
Instead of the usual waterfall of signals over a ~2.5 KHz range, I am 
seeing a narrow, loud band of signals between 1250 and 1700 Hz.  WSJT is 
continuing to report activity on the band but only in the same narrow 
audio region.  This is happening regardless of the RF band selected - I 
have tested everywhere from 30 meters up - and regardless of whether I 
select FT4 or FT8.

The radio seems fine on CW.

I've tried everything I can think of - ideas?

-- 
73, Pete N4ZR