Hp rollerball mouse model M8590PLJ

Flip the small rat upside down!
Remove the ball by turning the round plastic ball retainer counter clockwise. Clean the ball with soapy water, rinse it and dry it, and set it aside.
Look inside the mouse, you should see three white nylon or black plastic rollers, scrape any dirt that might be caked on to them, and clean them throughly with some alchool or acetone.
If you have a can of compressed air, point the the nozzle inside the mouse to expell all the dust out, if you have no air, use your mouth, blow hard!
Put the ball back on the mouse, the plastic retainer (turn clockwise to lock in place). and you're all set to go!