It is no secret that the "Mighty Mouse" ( Apple Mouse before Magic Mouse ) was widely appreciated for its 360º capable scroller and its squeezable buttons on the side until people noticed that the scroller wasn't as sensational as one might imagine. As much as it hurts to say this, the mighty mouse was a rather flawed design. The scroller has a tiny space running all around its periphery which allowed small particles to go on and stick to the scroller thus damaging its scrolling capability. For example, I get many emails ( and I myself have experienced this problem ) that the mouse is scrolling only in one direction or, more often than not, none.
So how do we fix this ?
Perhaps some fancy solution ? Opening it up and rearranging something ? Not at all. Your best bet is to turn it upside down, press it down hard on a piece of paper and roll it back and forth vigorously for about 10 seconds. Turn it back up. Scroll a few times and use your new mouse.