Grounding the trackball is to bleed off the static electricity buildup from the spinning ball. If you open up the trackball you'll see the ground wires attach to the rollers. Not grounding it shouldn't hurt anything but you if you get a static shock , which of course is minor. Won't hurt the trackball to leave it ungrounded.
Anyone know anything otherwise?
--- saint
Theoretically, it's possible to build such a charge that it could zap from the roller to the optical PCB, Frying the optical board in the process. But you need a
huge amount static, and probably a dirty/greasy encoder to zap that far. (If the encoder was metal like some of the
old ones, not as much would be needed, but still an enormous amount.)
Never heard of it happening, though.
Usually it's grounded so the players don't get small zaps while playing in cold, dry conditions.
I haven't grounded my happs or betson TB. My wico didn't come with a grounding wire at all. [shrug] If you like to wear a belt and suspenders, ground llike others have mentioned.