[Elecraft] Frequency Problem?

[Thor, N9IK]

I guess K1 #1065 still isn't out of the woods yet.  Now, there's a new twist:

The other day when I zero beat (using the spot function) and called a 
station that was calling CQ, the other station shifted down about 100 Hz to 
zero beat ME.  I thought it strange at the time, but yesterday I called CQ 
and was finally answered, but the station was (again) about 100 Hz 
low.  This morning, to do a test, I set up my portable antenna, took the K1 
outside, fired up my TS-130s rig inside, cranked the power down all the way 
on both rigs, and transmitted test signals with the K1.  I zero beat the 
K1's signal on the kenwood, then transmitted from the Kenwood.  The signal 
received on the K1 was, again, about 100Hz low.

What is out of adjustment on the K1?