Apple Power Macintosh 7500 Series - Manual (Page 148)

To unlock the mouse, follow these steps:
1 Insert a straightened paper clip into the hole on the plastic ring.
2 Press down on the paper clip while you turn the ring counterclockwise.
Turn the ring a very short distance. When the recessed area on the ring is
lined up with the recessed area surrounding the ring, the mouse is unlocked.
The mouse ring is unlocked when the recessed area on the
ring lines up with the recessed area surrounding the ring.
Recessed area on ring
Recessed area surrounding ring
Insert a straightened paper clip into this hole.
(The hole may be located here on your mouse.)
138 Appendix A