[steelybill]

I would agree with the abrupt failure of a timing plastic gear. They almost always fail when the engine is turned off for some reason, at least in my experience.
This problem is really getting interesting.

I still think an inspection of the valve springs and rockers is a good idea. Pulling the coil wire and rolling the engine over without starting will be a way to look-see how the rockers and springs are working, and if there is ample lift etc.