How do hydraulic flat tappet lifters fail?

Lifter bore is .904. Lifter diameter is .903.
Wow, I didn’t realize the tolerance was that tight. Half a thou ain’t much.

Look at the edges of the lobes on this cam

That’s not something I would’ve known to look for. While I’m not saying that was the case here, I do remember my cam lobes having pretty sharp edges. I simply attributed it to a freshly machined job. This time I’ll pay close attention and look out for burrs.