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How did you solve the problem? I am having the same issue right now with my MM. Thanks

Q-Tip & Rubbing Alcohol

Dip Q Tip in Rubbing Alcohol, turn mouse upside down and rub the scroll ball with the wet end of the Q Tip until entire ball is cleaned. Do NOT turn mouse back over, until you take the dry end of the Q Tip and dry the mouse ball.

This should solve your problem, That is how I solved it.
 
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