These look like a mouse but they are for reading proximity cards. Xerox copiers used them for access control years ago. They are based on the HID Global 4025A MCM module for reading cards. The full part number is 4025A1105.
We repaired about 100 of these for Xerox back in the day and have a good handle on how they work and how to test/repair them. If you are still using these Equitrac units or a similar unit that uses the 4025A module give us a call, we can probably help.