Why does smothering a small fire with a blanket or the lid of a pan put the fire out?
The ball in the mouse is not the only thing to get dirty, sometimes dust and dirt collects around the rollers also. Open the door on the bottom of the mouse, take out the ball and Set it aside. Take a small screwdriver and gently scrape off the gunk that collects on the rollers; there are usually three (two long, and one skinny). When you have all the dirt cleaned off make sure you shake the mouse; hole side down to remove the dirt from inside the mouse. Put it back together and you should be good to go.