[Water Warrior 2]

WHAT is a good question. I would think you found an example of metal fatigue in one gear out of tens of thousands worldwide made for the GZ top end. Chance of this happening again are probably next to nil in the future for you and many other riders. It is unfortunate the gear broke but you were able to fix the engine using knowledge gained over the years. Many of us, including myself, would have been at the mercy of a dealer for repairs.