How do hydraulic flat tappet lifters fail?

If you wouldn’t mind pulling the guts out of one of the lifters........ I’d like to see if we could tell who made them.

They’re supposed to be either Hylift or Eaton....... which used to have different styles of metering to the top, which could be used to tell who made them.

I’d also get ahold of Lunati and see what they have to say.
They’ll want it back, but that’s worth it if they’ll do something for you.