Well hats off to Elecraft, they've come up with a fix for the "offset fault" I reported. Seemingly they had a crystal supply problem in the last year or so and ended up swapping their supplier. Unfortunately the new supplier is providing Crystals marked 116.010MHz. These crystals are obviously 10KHz out from the original 116.000MHz ones.
The Elecraft K3 and K2 transceivers will only correct +/- 10KHz offset in firmware so any inaccuracy in the +ve side of the new 116.010MHz crystals renders the transceiver "off frequency". Unfortunately this was the case with my supplied crystal.
The Elecraft fix involves cutting a link and adding an adjustable inductor coil to "pull" the 116.010MHz crystal within the offset capability of the K3/K2 transceivers.
I decided that after paying the extra money for the crystal oven option, I would rather have a more accurate crystal inside the oven rather than "pull" the crystals frequency using a coil outside the oven. I have now replaced the crystal with one from a local supplier:
HC49u, 5th Overtone - 116MHz, series o03s
This replacement crystal now brings the XV144 up bang on frequency. Now to get on with using it :-).