Try taking it to see a broadway show, I hear that usually works

I find when they stop going down a nice dinner and some flowers can help....

A little too late

Shave. Nobody likes hair in their teeth.

Nice reference Now if Stern would just make another SP........

Glad someone got it

I guess your thread is devolving into unhelpful innuendos...

A couple things to check:
1. Is the t-rex saucer making good contact when the ball is in it?
2. When in t-rex diagnostics, are the up and down switches activating consistently?
3. In t-rex diagnostics, is the center switch getting activated?

My guess is that your up switch arm needs to be bent to where it's being activated for a longer duration when the motor is moving into the up position.

I had a similar problem with the up and down motor. I ended up replacing both. Expensive but well worth it

my JP

had an issue where when T rex was down the jaw wouldn't close

not sure if related but the mech got gummed up and was kinda locked in place

have you tried the assembly without the Rex Shell?

see with him exposed if the assembly is trying to work

That is the problem. If the t-rex doesn't know it is centered, then it won't go down.

It's going to be a matter of figuring out what's wrong with that switch. It will probably have to be accessed from underneath, but if you remove the plate with the foliage decals held on by 2 screws in front of the t-rex, you can see a little bit of what's going on with the center switch.

Is the switch arm being actuated when the t-rex is in the center? Is the switch arm broken? Is the switch bad? Is the wiring loose? Is the diode on the switch ok?

In both t-rex diagnostics and switch diagnostics you should be able to manually actuate the switch and see if it's registering. Maybe (hopefully) it's just something where the switch arm needs to be bent a little so that it makes better contact when the t-rex is in the center.

Hmm, well the T-rex not going down is the symptom... the problem is that switch. I'm kind of scratching my head on this one. A good test for the wires would be to check continuity between where they connect at the switch all the way to the connector in the back box.

You should also be able to test switches on the board by having the two switch connectors unplugged and bridging one pin from one header to one pin on the other header. If you can figure out which two are the center switch that will help.

I'm curious if the switch will register on the board. If not, the issue is on the board, otherwise the issue is in the connector/wiring.

Mine is not going up and down. When it moves it is a "jerky" type movement. Now in test, it moves very slow and jerky, or not at all. Do I need a new up/down motor?

Here's what I suggest:

Test 1:
Rather than measuring voltage, I suggest measuring for continuity with the game off from the wires coming from the connectors at the MPU all the way to the Up switch. If you get continuity, then you know the wiring should be fine (though a pin on one of the connectors could still be questionable, but I'd expect a whole column/row of switches to be flaky if that's the case).

Test 2:
There are two connectors for the switches. I haven't confirmed how they're wired, but one should be the rows and one should be the columns for the switches. The Up switch should have a wire going to each of these connectors. You can check to see if the issue is in the playfield or if it's on the board by disconnecting both of those connectors and manually momentarily bridging a row and a column with a wire. If you know which two pins are the Up switch, you can start the game, get it into switch mode, bridge those two pins and see if the Up switch registers. If it registers, then you know the issue is in your playfield wiring, switches or the connectors. If it does not register, then the issue is on your board.