Are you talking about the kevlar spur gear? If so I have ran it for a while now.....its a spur gear. I mean the only thing that I noticed with it is its harder to strip and it runs a little more straight then the blue ones did.
Jitsu....not saying that your dumb or anything but make sure the pinions are the same pitch.....lol. I have used a 23t with the 128 spur with out any problems....maybe you have a bad gear.