Turn the PC off, then pop the Ball out of the mouse-you have a small piece of plastic to turn (usually clockwise)-then look inside. you should see bar on the top and 1 side, plus you may have a spring-tension wheel to keep the ball tight against the 2 bars. get Q-tips and alcohol and clean the bars and the little rubber wheel, if you have one. Clean until all look nice and black instead of the brown you are probably looking at-you may need a small screwdriver to hold each still as you clean 1 part (there is a large wheel at the end of the 2 bars you can lightly brace against, and do the same agaist the SIDE of the little wheel to hold each still as you work), then turn it about 30 degrees and clean the next portion. Once you're sure all has been cleaned, reassemble your mouse (be sure all the alcohol has dried), and turn PC back on. You should notice a Marked improvement, and have officially completed Mouse Maintenance 101....Retired AF and A Texan...