Tracker ball and 4 D
Hello, if your trackball is erratic, it just might need some cleaning.
1.) Remove the fixation ring by turning it counterclockwise. (use 2 flat head screwdrivers), then remove the ball, clean out any dust and dried gel and remount.
2.) Mount the fixation ring by turning it clockwise.
If you have to replace the whole trackball assembly, then you have to lift the upper panel to acces the trackball.