Let me first off by saying that you are not alone and that I feel your pain. This is my first post on Pinside as I normally just read through forums but don’t ever chime in. I received my Jpp on 7/14/2020 and finally after replacing several boards and the T-Rex I feel like I finally got it working 100% yesterday 9/8/2020... knock on wood. I won’t go into a ton of detail unless requested but just know that you are not alone. One thing I would check is that when the T.Rex is thrashing that his jaw isn’t hitting the left ramp. I noticed that sometimes my rex’s jaw would hang a little low ... just enough to hit the ramp and mess with his center position. I had to adjust the lower plate behind the rex in order to raise him enough to clear the ramp. My old Rex wouldn’t keep the ball in his mouth.... I suspect the magnet went bad. I spent nearly 8 k on a new in box pinball machine which gave me problems pretty much since day 1. I don’t mind working on pins as a hobby but to spend that kind of money on a brand new machine I expected perfection. Maybe that’s not the reality with pinball machines but again I expected perfection for that kind of money. Thank god for their tech support (Pablo) and the six month warranty or I would have been SOL. Now that its finally up to snuff I am enjoying it. The highlight for me is the six ball chaos mode... yesterday I was killing it... smacking all the balls through just about every way they could go... ramps , orbits , control room.. everything...it was awesome and I swear it lasted like 10 minutes... I was wore out but felt so satisfied blowing up the machine like that and having everything go crazy. Anyway I don’t want to ramble on to much but just wanted to let you know that your not alone with these issues. Thanks for reading

Yeah, I've had something similar with my Star Wars Pro. A weird and frustrating issue with the loop posts. I won't go into the details, but it was seemingly unique, and hard to figure out what was wrong. I think it's fixed now, but I need to put more games on it to make sure. And I concur that I never expected to really have any major issues with Stern NIB games, maybe some adjustments here or there, but nothing serious. I guess I know now that just because it's a new Stern, doesn't mean you won't have problems.

The thing is, I feel like it's easier to diagnose and fix issues on my older games. With these new Sterns, if it's not an opto or a mechanical clearance issue, then it gets harder to figure out what's wrong. But I suppose part of it is that with the older games there is a lot of documentation, and I feel like it's easier to spot on-board issues with the older pins too.

Still, at least we have actual Stern tech-support. We don't have that with our older games, but I suppose places like Pinside are kinda the next best thing.

I think it’s great that you started the topic as I’m sure it will help many people. I’ll try to contribute to it by adding some more of my findings. Lamp board 9a can affect the movement of the T.Rex. I was having an issue where the leds On 9a would come on and off and or flicker. Whenever they would go out the T.Rex would not move vertically ... that’s because the node 9 board runs to the 9a lamp board and then to the vertical board that leads to the T.Rex. Once I replaced all of these board (just to be on the safe side) the Rex moved in every direction like it should. I’m not sure why that lamp board had issues right out of the box but I did notice that node board 9 had wires connected to the cn2 connection instead of the cn3 like it says it should be in service manual. I don’t know if it makes a difference but I connected it to the cn3 since that’s how they have it listed in the book. I also had an issue with the pinball never making it down the plunger lane straight enough to carry enough velocity to reach the wire form. People have already covered this... here’s a link

Don’t over tighten the screws that mount the T.Rex as they are small and will break. If I think of anything else that’s useful I’ll post it here. Thanks for starting this topic as I don’t believe this was here when I first got my Jpp and it’s definitely needed.

image (resized).jpg

Excellent, glad to hear that your JP is now working properly. I actually didn’t remove the vertical motor when I installed my new T.Rex.... I left it intact and instead removed the screw that holds the top of the plastic shaft. Once the new Rex was mounted I simply reconnected the plastic shaft. The outside screw is a # 10 and the inside one I think is a # 6. (I used an adjustable wrench as getting a socket on it was a pain). It’s all good either way but thought I would document this as it may be a little easier for the next person.

I’m so glad you mentioned about the tongue because I knew something was different with the new T.Rex but I couldn’t quite figure out what it was. It’s just a sticker and I was able to remove it from the old rex with a hairdryer and stick it on the new one. Thanks for the heads up on that... glad I read your post before I sent the old one back.

1A63FB69-5FF0-4A08-BA9A-5D62C7D8304C (resized).jpeg

5501F784-42C4-4A90-9598-B1A5A0D1FD49 (resized).jpeg

5641367A-2636-4E87-BEC4-2B737DD21AD9 (resized).jpeg

It’s pink... lighter in the front and darker in the back. See above for picture

Curious as to what issue would warrant a complete replacement?
Sorry OP don't mean to derail your thread.

Turns out you are correct. Switch 59 aka T-Rex exit ramp opto is stuck ON. It appears to be the piece that is on the backside of the ramp only accessible from behind the back panel. It seems that the slightest touch, vibration, up pressure or down pressure switches it to off. But when released it goes back to the ON position. Almost as if the weight of the cables alone are switching it on.

did they send you just the head + the stepper in the head or the complete assy ?
So wierd that my problem isnt solved by a new head, might be from the same batch then i guess?

All fixed. Black motor soot likely from the T-Rex had covered the opto sensor. Cleaned it with a rag and back to perfect again. Two mins of work for hours of troubleshooting pain.

So glad you got your Jpp up to snuff

Use and abuse the crap out of it while it’s under warranty seriously . On a side note I went to a pinball tournament today and guess what... I met the guy who’s video I posted above. His name is Craig as well and his channel is hurry up pinball. Such a small world but glad I can be a part of it. Rock on everyone.

I literally just got my premium in June and the trex just started doing the same thing. I'm sorry this is absolutely unacceptable to me since I bought this brand new for $7400. I will never buy a new Stern pin again. I understand the machine has lots of moving parts etc but this should not be happening to a brand new machine that's less then a year old

I've just started having a similar issue with my JP Premium. Haven't gone through the suggestions within this thread yet put plan to. I do know it is making a pretty bad noises when actuating (can't seem to figure out how to add a video), and appears to perform a horizontal test under both vertical and horizontal testing, for some reason.