use a capped pen or eraser side of a pencil and turn the unit over and push the trackball out through the hole on the bottom. Use a paper towel or napkin to clean the trackball surface then use a q=tip or your finger nail to clean off the white (YES THEY ARE WHITE) sensor pads where the trackball sits. Lastly, make sure the tracking sensor (clear-reddish window looking thingy) is wiped off and clear of debris. The whole process should take less then 60 secs.