Originally Posted by scot

Crank is 100% perfect, using a pes515. Bottom bracket is bb infinite bearing setup with Shimano bearing in T47i (proper trek frame sized version). Has the delrin topcaps installed. There is no play, no noise, and it is dead straight. No other spacers etc. Torque wrench set everything and there is no excessive play in anything. Spins smooth even under extreme load.

Derailleur has 8k miles on it. (stated above, but possibly not clear).

It started throwing the chain off the big ring randomly, which is why I changed the crank rings (Tried both a 50/34 and an unused (came in a package deal) 52/36 chainring.

Battery is fully charged btw. Tried unplugging and plugging the FD back in and similar troubleshooting.