Trackpoint is haunted

My X200's trackpoint seems haunted. On most parts of the screen it works smoothly, but in some parts it is hard to push to a target. Sometimes when I try to push the Trisquel menu button at the bottom of the screen, the cursor drifts down off target and disappears off screen. Other times, certain parts of the screen cause the cursor to bog. But if I move elsewhere, it is fine.

Changing mouse setting doesn't help. Acceleration profile is set to flat, but the same thing happens using default or adaptive. The issue varies depending what is on the screen. Thanks.