My Microsoft mouse...a 2 button/scroll/ball version...several years old...had been giving me fits...not very responsive...very difficult to precisely control the cursor. I had taken compressed air...taken the ball out...blown out the insides...very little improvement. So I figured that it was just worn out. Then...I took the ball out again and I saw my problem ( just missed it before). Lint had built up on the two small rollers and the little wheel where the ball makes contact. I cleaned the lint off...and VOILA!! PRESTO!!...a new mouse! It's now super smooth...just like new.

Amazing what a little bit of cleaning can do ..saved myself some money!!