This is what I think:
Originally Posted by BillL
.... The thrust surface "could not support hydrodynamic lubrication due to poor geometry from the machined surface".....
A thrust bearing cant work if it's only half way around the piece bearing against it. The oil film wouldn't make the trip around the circle if there's no circle. (
To me the telling part is this photo, there's no good reason that the crank hasn't touched all the way around. Even if you ran it with no oil in it, it would contact the thrust all the way around: