[Elecraft] Strange new drift on my K2

[Andrew Moore]

I recently noticed some drift on my K2, but it's not happening the way
I'd expect.

This morning it happened again, as follows.

I turned the K2 on the K2 with volume turned down almost completely
and left it that way for a couple hours, tuned to 7040 kHz.  Then I
turned volume up to a normal listening level and immediately tuned
down to a CW signal at 7024 kHz.

Tuning resolution was set rather course at 100 Hz.  When I let go of
the main tuning dial, within seconds the frequency starts climbing up
the band at a rate of about 100 Hz every 10 seconds (rough estimate).

I changed tuning step to 1000 Hz, and the apparent drift kept
happening, but this time in a 1000 Hz step *within the same time
period as before*.

It's almost as if my encoder is drifting... not the radio.

After a few minutes things seemed to stabilize.

I just tweaked the main dial again, and drift started, this time in
the other direction.

The rig seems to go into these drift fits only when I tweak the knob.

I've never seen this behavior on my K2 before.  It's been very stable
since I built it more than two years ago (serial number 4958).

A couple weeks ago I did a very thorough realignment of everything
(peaked inductors and caps, tuned filters, calibrated S meter,
measured MDS, etc.) using test oscillator and calibrated noise
generators ('til I fried my N-gen.. D'oh!).  Top to bottom tune-up.
I'd swear it sounded better than ever -- or maybe that was just the
conditions on 40... but this drift seems to coincide roughly with that
realignment.  Maybe a complete coincidence.

Help?

--Andrew, NV1B