They are the ace when it comes to tracking your mouse cursor. However, they only last for so long and what I mean about that is the ever so annoying scroll ball on the top. I have had 2 of these mouses by now and both of those scroll ball’s have stopped working.
I dug up a couple of ways to actually fix these sons of ball’s and they seem to work quite well. However, the second is a hazard and you need to know your tools before getting in to that one. You can easily break the mouse and the warranty expires as soon as you get your dirty fingers inside the shell.
So remember, be careful!
Dab a cloth in alcohol or water, do not over saturate the cloth. Run the mouse upside down over the cloth.
OK, when all strategies fail their is only one thing left to do. Throw it as hard as you can into the wall. Walk to the store and buy a new one. (BUT: Check if your warranty is still valid, in that case carefully package your non working Apple Mighty Mouse in the box it came with and take a brisk walk to the store and get a new one.)