How do hydraulic flat tappet lifters fail?

Is there a way to ensure that they do spin, or is this just a thing that happens out of our control? And yes, I'm not looking forward to what I find when I pull it apart.



I was wondering about that because I had found conflicting information before the install. The lifters are Comp Cam lifters, and the instructions said to soak them overnight.

Edited for correctness. I originally said concave... the correct term is convex.

The lifters spin because the bottoms of them are not flat, they are slightly convex. That's what causes them to rotate slightly every up and down.