If your mech is that mucked up, I'd call 1-800-kickers and work with Stern on it.
In terms of the T-Rex ramp opto issue, I think a lot of people forget there is a test for that. Go into the menu and do the left ramp test. You will manually launch a ball into the shooter lane, this game puts the ball on the right flipper. Shoot the left ramp. It will count the number of entry and exit opto switch closures. If your game has more exit closures than entry I'd stark fiddling around with the opto etc. If not, I would suspect something else.
Also, removing the two black spacers from the clear plastic at the front of the ramp isn't an ideal solution. They are there because the ball hits the plastic too easy. While it does keep the ball from jumping over the opto, it also slows the shot down and can lead to certain weaker shots not making it up the ramp that might have otherwise. At this point, there are so many suggestions on how to fix the opto that I would leave the spacers in.
Quoted from beelzeboob:
I'm about to shoot my T-Rex in the head. Sometimes he doesn't open his mouth. Sometimes he opens his mouth but doesn't swallow the ball (I have the old ramp shield...I guess I should try to get a new one). Sometimes he just rests his head to the right side of the ramp and doesn't open his mouth, like he's taking a nap or something. And sometimes he opens his mouth, swallows the ball, and does everything just as he should.
It's infuriating because it seems like I have EVERY problem with my T-Rex that everybody has described before, and I'm not really sure where to start outside of doing a complete rebuild and working out the opto situation.
Anybody have any ideas or fixes offhand? I don't think anything in software (the bias adjustments, for instance) will fix this.