It doesn't take long to go from enough tooth to drive to nothing like that one when it starts to slip! I ran a TD-9H Dresser that was due for an undercarriage. Had the new one ready to go, I figured run it till it really needed it. It went for most of the summer then one day the sprocket slipped a couple times and that's about what it looked like by the time it got back to the shop, it was done. I figured it was free wear, he got about 600 hours of life that would have been thrown in the scrap heap. I have never let another one go that far again though, too hard to load it on the trailer!