If it's not the flippers, perhaps the metal guide near the spinner lane is forcing the ball down. For a clean shot through the spinner, what F.I.R.E. lane does the ball usually go through?

This must be frustrating.. I made a short video of the ball trajectory. Hope this helps.

No multi-cam.. Just editing.
I noticed in the video, the ball hugs the top wall all the way into the lock. Perhaps it's just a matter of flipper strength. I can hit the spinner and get over 40G's - (40 spins)

I took your video and did some slow motion. Look at the spinner. For the one ball that was successfully locked, the spinner had more rotations compared to the other shots that didn't make it. I think on my Firepower, if the spinner only rotated ten or so times, it would not lock as well.

Hey Geocab, on another thread you posted a picture of Firepower.

https://pinside.com/pinball/forum/topic/upload-pics-from-android-phone

Your PF looks very clean. Do you have have a new PF with clear coat?

I'm curious, does a new PF with clear coat play slower? Perhaps the PF is slowing down your shot...