Crank Thrusting Foreward Issues

It is entirely possible that the thrust was bad from the gitgo. It should have been checked, torqued with a dial indicator.

Since I have a tiny bit of experience with crank grinders...it's also highly UNLIKELY that the thrust on the crank was bad while it was up in the grinder. Almost everyone I know kiss the thrust while the crank is in the grinder. It is possible it was missed, but it falls into the statistical category of highly unlikely. I have seen some crank that were so poorly done that they were sent out to be welded strokers (yes I am that old).

I still say most likely the converter was not in the pump.

The big deal is that the OP nail down EXACTLY what when to poop on him or it will happen again. I don't think anyone wants that.