[olddog]

I'm no expert. Well let's put it this way. I don't get bothered at night by a phone ringing off the wall with people offering me big bucks to work in their engine shop. With that said here is my logic on the lifters. When the cam is pushing up on the lifter's roller and the pushrod is pushing down on the top of the lifter (via spring pressure), the forces on the roller pin are exactly the opposite of the piece that broke off.

Unless the roller pin is bent, excessive spring pressure is not going to cause this. If the pin flexed and did not yield (spings back to straight) it might cause this, but as small as these parts are I just wouldn't think this could happen to good parts at any reasonable spring loads. I would think that type of spring pressure would collapse the lifter. I may be wrong on that, but intuitively that would be what I would expect.

Since I cannot think of anything, other than flexing or bending of the roller pin. that would put a force in the direction needed to cause this break. I am thinking sub standard material or machine work. I would blame the lifter until something else is proven to have caused this.