AmiNTT:
Remove the 2 teflon sticky pads from the front of the mouse, there are 2 philips screws underneath. Once done, carefully lever the back apart and the top comes off.
The wizard mouse is simple to maintain, standard microswitches, opto-coupler and a 7414 hex schmitt inverter, all replaceable parts.
To KennyR:
Wizard/Compute! disappeared about 2 years ago from their shop. About 6 months prior to disappearing they stopped Amiga support/products.