Only other thing that might cause it to move out of mesh is if the CB outer bearing retaining clip either came out or was missing allowing the whole shaft to slowly creep out, but I tend to think that the bolt is probably more likely especially with known historic bolt problems (triple sprocket bolt)Agree. Possible that the cb bolt backed out and tooth engagement was lost. Shaft to sprocket is splined with a master spline so no way to mistime that. Possible on the teeth, I guess but there would be a problem right away with either hitting or extra vibes. One thing I think we can all agree on is the CB timing is the issue. Reason, other then the bolt backing out, not sure.