The other thing this mouse is missing is a scrolling capability. Since I've been using it as my daily driver I've noticed that I really do miss that ability, and it would be great to be able to hold a modifier key and scroll with the wheel. I was going to put a microcontroller in there to control the LEDs already, so now I'm considering making a new board entirely so that I can read the positional encoding wheel and assign a modifier key. This project is growing. 

Today I learned about How Computer Mice Work and visited the linked article about directional detection, so I thought my new understanding of transmissive optical sensors would help me find replacement parts to solder onto a new board. Instead I discovered that no one seems to make the kind that came out in 1998, and so a drop-in replacement that uses the same wheels that came with the iBall may be asking too much. 

What will happen next? Will I be able to find a sourceable optical sensor to use with the existing wheel, or will I have to get a new wheel assembly? Will I keep the original components from the iBall and swap them to the new PCB? How will I even read the data once I get it? Stay tuned for more adventures in quadrature.