Here's what a Modify pinion gear looks like after I slightly misaligned the gear in my pinion removal tool and didn't notice the misalignment until it was too late.
Initially, a tooth-shard snapped off, and then I had to rotate the gear within the tool to get it off the motor shaft, with a few more pieces snapping off in the process. Motor shaft belongs to a G&P M160, which survived just fine (I put another pinion on it..).
I also snapped a selector plate today, shortly after this picture was taken, but Krazy Glue took care of that.
Good times...
edit: In the photo, the pinion gear on the right is a stock G&P