Here's a Youtube I found that help fixing a irresponsive Mighty Mouse scroll ball.
If you found this page, you'd probably know that after some time, the scroll ball usually becomes less and less responsive and sometimes just outright not working altogether. There are multiple ways of fixing it but usually either not effective or require technical skill or need to open the mouse. Above is a way to fixing the Mighty Mouse without having to open the mouse up. Hope it works for you.
