[Elecraft] K2 Main dial problem

[df5rf]

Hi all,
Since I came back from /p vacation end of June , I didn't used my K2 until
yesterday. Since then, it has been rested in a portable bag. After I took
it out I didn't noticed the problem, but now I'm a bit worried what 
happend to it.
The main dial moves very hard most of the time, but sometimes it is possible
to get it moved easily, as it has been before. I'm not aware of any 
mechanical
shock or other kind of damage that would explain it. Unmounting the knob
doesn't change it.
Is there a chance that the optical shaft encoder just needs some kind of 
clean-up?
Or must I call Elecraft and order a new one?
Thanks for all the advices.
Gernot
DF5RF

http://www.qsl.net/df5rf