Okay my trunk lock rejects are mostly fixed. As I kind of thought initially (having nothing to compare it to, I wasn't 100% sure), the tines of the fork were bent towards the right wall of the chest entrance on the back, causing the ball to hit the wall on the right side of the chest hole and reject. iPhone slo-mo to the rescue.
Removed the assembly, bent both tines back toward the left, reinstalled, and I can make 3 out of 4 shots into the chest lock now. I might fine-tune it later, but it's pretty much fixed now.
One other thing that's cropped up is black screens on the bonus screen? Just the bonus text and music, but no random video playing behind it? Is this a timed bug? I've had the machine on for hours and this started happening...
Also, what's the deal with the black screen in attract mode that is all black except for "GAME #84" (the number of the game)? I have that off in the settings, but even if it was on, really? An all black screen with white text with the game number but nothing else?