Jim,
I don't know if this will work. One of the photos I saw of these assemblies on an eBay site seemed to show generic microswitches as the electrical part of the assembly. When my trackballs started to fail (due to lots of clicking), I opened one up and found a generic microswitch inside. I was able to repair successfully with a part from digikey.
If you can determine that one of the switches is failing, this approach might be worth a try.
Stephen
