If it does that in FSX, it should also do the same in the
calibrate windows if it is the stick. If it never does it
when calibrating, it would get me to wondering.
But, I've never had a control problem in FSX that wasn't
the sticks fault when it happened.
If the pots are acting up, you would want to spray them
out with a good switch cleaner like de-oxit, tuner cleaner,
or whatever. Don't use anything that will leave any sort
of oil or residue.