What's your playfield pitch? And how's your sanctum wear? Those can be culprits too.

Also check the trough switches behind the magnet IIRC they can cause issues as well with the wall target.

Just a little sanctum wear can be enough to throw it off

I would never have believed this could cause so many problems if I didn't just go through it. Even if the sanctum looks good, it could have enough of a divot to cause the ball to hang up. Just an extra half a second stuck on the sanctum is enough for the machine to miss it as it passes the optos the second time. Plus, if it misses it in this way, it will throw all sorts of other errors at you too, like the wall target is bad, etc. that have nothing to do with your problem. It's a confusing cycle.

You can set your playfield steep and see if it fixes it. I ended up cutting a couple little circles of painters tape and putting them under the sanctum sticker. Just elevating the magnet area so the ball rolls faster when released fixed all problems for me.

Does everything check out in the magnet test?

Are you positive that the switch that activates with the dropping of the target works perfect?

I had this same issue.

That switch activator arm should only be activated by the target itself.. Not the targets height adjuster bar.

Can be finicky.

We need to make sure we're on the same page here:

The "activator arm" I speak of is the switch's metal arm that is pressed in causing the switch to function. IT should only be activated by the red brick target dropping... nothing else.

With my issue, this arm was bent/misaligned causing issues. It would hit against the "target height adjuster bar" which is a metal bar at the bottom of the target that is used to increase/decrease the height of the target when it's up. This adjuster bar shouldn't come into contact with the switch activator arm.

Pop up your pf and manually drop that target (game off). Make sure when it drops, it presses the activator arm and you hear the "click" of the switch working. Do this repeatedly until you know if works right. Also, when the target is raised back up, does the switch unclick?

I think your issue is you need to adjust this activator arm to work a bit more reliably.

leveling leveling leveling!!!

Yes. I had problems with my Shadow wall many years ago and I seem to remember the trough switches being an issue (back in the RGP days). Put the game in switch test and check the switches function correctly using balls.

pitch pitch pitch!!!!

Even if the switch is good, if the target linkage is worn and does not lift the target all the way every time and it drops back down, the magnet will energize for an excessive amount of time and then just drop the ball down the playfield.

OP, next time you're in the backbox, try pushing on the ASIC chip on the MPU. It's the big, square black one near the middle. Push on opposing corners gently a couple times. I was having intermittent sound and DMD garble on a STTNG and reseating the ASIC fixed it.

I would recommend getting a couple pieces of scrap wood and some bond-o. Practice filling a few divots and when you're comfortable, fill it on the playfield and put the decal on it. I just picked up my Shadow and that's what I plan on doing.

The shape I found best for building up that area with mylar/stickers, etc. is below. That way it allows the ball to roll off very easily. Just a temporary fix though, and I think you're looking for a more permanent one.

shape.jpg

Yeah, oriented like the picture. I used an exacto blade to cut that shape out of about 4 layers of painters tape and stuck it down under the sanctum sticker that someone here made. I kind of wonder if what's happening is more common than people let on. My sanctum was repaired before I owned it - I'm sure it was completely flat after the repair, but over time whatever material was used in that area must have compressed between the ball and the magnet. So if the repair isn't 100% solid, the problem comes back pretty quickly, and no doubt quicker than the original playfield wear. I'm too lazy to tear mine up again, so leaving it be for now.

That magnet has an adjustable core. If it's so strong it's compressing the material badly, you should try backing it out a round or so.

Of course there will still be wear from friction but Mylar can handle that. Just a suggestion.