[Elecraft] spurs on a K2

[KT5X]

Was reading where with a spectrum analyzer form a 781, signal was seen as very clean.  I little less precise, I have listened to my K2 with an MP adjacent to it, and there are no spurs to be heard.

BUT...

A few days ago I worked a K2 built and used by an OT in his 80's.  He had a very strong spur about 2 khz up from the fundamental.  I suspect this is caused by an adjustment mistake such as the VCO adjustment that leads to chirp on 40 meters.

Can anyone tell me what adjustment mistake might likely lead to that spur?

TNX, 73, Fred - kt5x