My trackball has green boards, and there are instances were it seems to freeze? Or something odd, if I spin it too hard. Could this be the issue? Come to think of it... I do think mine is a USB... I was figuring it had to do with being over voltage or something, but perhaps swapping in these red boards + parts would solve this issue?
If you're seeing backspin when you move the trackball quickly:
1. Verify that the encoder wheel is mounted securely on the roller so both are always moving together.
2. Check if the rollers are moving smoothly, not binding or causing the ball to skip.
3. Make sure you have the frame ground (2 green wires ==> ring terminal) connected to ground so the static charge generated by moving the trackball is safely drained to ground.
If those three things are OK and you're still experiencing backspin, then changing out the optical boards and optical encoder is the next logical step.
There's a post explaining some of the technical aspects of backspin
here.
Scott