Less windings should be stronger. Assuming coil is good. Even new coils aren't always good. Rare, but it can happen.

LTG : )

There's an adjustment to the ramp that is very simple to do and extremely beneficial. Here are two manufacture service bulletins specifically for this problem.

http://www.sternpinball.com/downloads/sb64.pdf

http://www.sternpinball.com/downloads/sb63.pdf

Great game

Kim

Hey Sparky...I had the same problem, like you, only during multi-ball. Timathie and I took off about 50-60 winds off of the 22-600 and I am not having any issues now.

I have a beautiful GNR that still fails on launch every so often. I've implemented the Stern bulletins, I'm running the latest software (3.0), I upgraded the coil to 22-550, I have a "Rev 2" wire form ramp (chrome), I moved the switch in the shooter lane closer to the ball rest, the pitch is 6.5%, yada, yada….

The only time failure really matters is during multi-ball, but when it happens, it's a real bummer.

The original 22-600 coil is clearly strong enough…the upgrade to 22-550 made very little difference.

Any idea what causes this inconsistency? Especially when nothing else is firing? Are all GNR's flakey in this regard?Since there have been 3 versions of the wire form, certainly seems like it was a design flaw from "day 1".

Sometimes it works great (ball flies up the ramp), sometimes is sputters. Mine is currently failing only 5-10% of the time, but given how much effort I've put into getting it to work, it's pretty annoying.

Any help would be greatly appreciated!

I also have the problem, that the strength of my shooter coil seems to be very inconsistent. Sometimes the ball goes easily all the way to the left orbit, sometimes it barely reaches the top lanes. I have the rev. C shooter lane, so the ball at least almost always makes it over the hump.
I looked a bit closer at my coil and it seems that the coil is too short to really be fixed in place by the coil retaining bracket. My coil reads 090-5023-00 instead of 090-5023-01 in the manual, but I don´t know wether that makes a difference. The fact that the coil is not completely fixed in place could cause the inconsistency, because the plunger sometimes might scratch the retaining bracket and thus loosing force. I hope my English is good enough to make it clear what I´m trying to say.
I will try an extra washer between the coil and the retaining bracket to see if that solves the problem. I´ll report the result.

That's what my "stock" coil reads (090-5023-00).

My coil is fixed…there should be a curved, metal washer that sits between the coil and the retaining bracket (to secure it). I believe a little wiggle is ok…doesn't need to be 100% tight.

I made the following tweak to mine that seems to have nailed it (along with the other tweaks)…the metal apron the ball rests on was pushed too far back. The ball was actually touching the plunger. I bent the metal apron so their was a 1/8"-1/4" gap separating the ball from the plunger. This allows the plunger to pickup some velocity before striking the ball. So far, it's been very strong/reliable. Still variable speeds, but the minimum speed still does the trick.

Good luck and report back!

the metal washer is there, but it´s not able to secure the coil, so I switched the coil tube to this one:
sleeve_70673.jpg
Now at least the coil stays securely in place - still I´m having balls that barely make it up the shooter lane.
I´ve looked really close at how the ball goes off the plunger and up the lane and I´m getting the impression, that sometimes the ball hits the first "ring" of the shooter lane, which of course slows it down substantially.
This could be caused by some misalignment of the coil and shooter lane and I´ll have to check this a little more on my GnR. Just wanted to mention it, because it might be the actual cause for some of you folks, too.

This is just DE auto plungers. You can swap everything out, rebuild everything, and they still have issues. PITA!

You could also test the resistance of the coils to confirm which one is more powerful. Just because the label reads 22-500 does not mean the person on the assembly line was paying attention. Higher the ohms, lesser the strength.

I agree, I think this is the real issue - and the "stronger launch coil" fix can sometimes even contribute to the problem, since the ball is hitting the slope harder and has the potential to bounce back/up off that slope even more. There are a lot of other factors that are in the mix, like the slope of the ramp, alignment of the coil & plunger like you mentioned, condition of the shooter lane, etc., but I think ultimately what ends up happening is the ball occasionally "getting air" during the upslope and smacking the top of the wireform.

I'd be curious to see a high-speed video capture of failed launches to see if that really is what's happening, or if we're totally off base. And if it is, I wonder how a modified launch habitrail (with the top rails removed, maybe back to the second ring or farther) would perform.

Does anyone have access to these bulletins? These links are dead.

I had this problem with a GNR at one time. Perhaps a bit unconventional, but I snipped off a few of the rings on the return spring of the launch coil. I figured less resistance on the plunger could only help things and it did! Good luck!

Everyone does. El goog is your friend.

http://files.flipperspill.no/Support/Pinball/Serviceb/Stern/SB_DE_SEGA-STERN.htm

Hi , I had this problem and have fixed it after I remember reading one persons idea.

The ramp end closest to the plunger has 2 bolts going through the playfield to secure the ramp in place. Undo the nuts and allow the 2 rails to be higher on the top of the playfield. You may need to push the ramp up from the bottom of the playfield. ( This effectively allows the ramp to start earlier so the ball rides the rails earlier.)
Such a simple fix but why I didn't do it earlier and persisted with the shooter plunger , the wire switch etc etc I'll never know. It gets up the ramp everytime now.

Now I have to sort out why the F9 fuse blows after multiball - something to do with the magnets I expect. Help please.