•How to Gut and Clean your Mighty Mouse (or Apple USB mouse w/Rollerball)
http://creativebits.org/toolbox/mighty_mouse_gutting_and_cleaning
I'd held off on buying a new one, then got this last edition Mini Server
that has Mavericks included; with so many places you need to drag a
page round, the scroll-wheel multiple button mouse is a necessity.
But I got a 'mouse-in-a-box' from the grocery for $12. that works OK.
However, today I found a 50¢ Mighty Mouse (apple) in a second hand
store and before using it, will at least clean the roller-ball. The above
link (in Comments) has good suggestions on cleaning just the Ball...
So, this will not require dismembering and reassembling to do it.
{I'd thought the web page had gone away, since I'd had a few bookmarked
some years ago; this one still exists but the other repair page is gone.}
PS: Wish me luck, since the roller-ball may be fine; the rest may be shot! 🙂