Take a paper towel, squirt Windex on the towel and place it on a table. Turn the mouse upside down and rub the mouse ball/gear briskly, but gently on the Windex spot, don't overdo it, just one squirt of Windex. Move the mouse to a dry area on the paper towel, keep rubbing; then blow air into the mouse & repeat...It should be fine...If you can avoid taking it apart, do that.