Ray, I wouldn't use WD-40 on electronics, there are cleaners/lubricants specifically made for delicate electronic components, like Deoxit F5 (for pots) or D5 (switches and encoders). The best route is probably to replace it, but I'm kind of curious if cleaning would solve this issue.

I remember back in the 90's I had a Roland D-10, to adjust the drum machine tempo you had a slider pot, and that thing was worn out. I remember during couple of gigs in the middle of a slow song like t = 70 beats/min, the drum machine would go to 200 or something beats/min, just on it's own. You can imagine the faces on the people who were dancing on the floor... :)), but later I had it fixed, it was very awkward though...

Since I got this KN7000 my cat is also very fond of it, not only about the sounds, but she is taking a lot of interest in the Bass Reflex hole on the back. I'm sure there are no mice in it, but it's funny as hell to see her excitement...