Hey greanie, have a look through the Jurassic Park club thread. There have been a number of conversations diagnosing people's issues with the t-rex. It is also where the most people who have immediate experience with the issues will see your question and help you out

https://pinside.com/pinball/forum/topic/jurassic-park-club

I don't know about that. Reads like he's collecting the ball and chomping all the way so the jaw coil is working fine. It's likely that he's not positioning upright enough for the ball to roll back into his throat. Could be something obstructing full motion or slack in the mech.

In that case check some of the discussion on the Improved T-Rex thread: https://pinside.com/pinball/forum/topic/jurassic-park-improved-t-rex-work-in-progress

I'm sure I read one or two folk that had issues with the T-Rex not getting the ball down its throat after installing the mod, possibly related to not moving 100% upright.

In any case, I'd recommend reposting your predicament in the JP Club thread, you'll probably get more relevant eyeballs on it to help you out