How do hydraulic flat tappet lifters fail?

No not like that, not that fast! The lifter didn't rotate for whatever reason. That probably started day one.
Thanks. A couple questions on the bores - am I right to say they should be .906" for .904" lifters? And what should the surface be on the walls of the bore? Mine aren't machined smooth to a shiny bright finish, but they aren't rough and pitted either.