Me too...have only ever owned one mouse and have been using it for donkeys years but i regularly clean it out.
Incase you have never done this you just twist off the bottom and let the ball fall out....give this a wipe over...then have a bit of a blow inside the mouse...you will see lots of built up fluff, dirt and gunk on the 4 little white wheels inside...its a tricky little job but you have to kind of rotate each wheel and scrape off the gunk with your nail as you do it...once all 4 are done have another blow and shake it upside down so any debris falls out then re assemble the ball and bottom...it will feel brand new..
oh and dont forget to clean off the bottom of the mouse...the little nylon pads get gunked up and cause friction...clean these off and it will whizz around your mousemat like a rocket !
