Try all new ribbon cables. They fixed a bunch of wierd issues I was having with my judge Dredd.

Great Plains Electric has all four in stock. Where did u order from?

Also, if you have another WPC pin , you could temporarily try the ribbon cables from that machine.

Did you get the new ribbon cables yet?

Still no delivery ?

Yes, definitely get the plastic trough insert, it helps big time. But when you put the plastic insert in the trough, put a piece of blue painters tape on the end to stop it from sliding back out. Mine would always back out after a few games until I added the tape.
Also, remeber there are 2 ribbon cables that go from the DMD board so it could have been either one that was bad, or both for that matter.
I'll keep my fingers crossed for you.

I was going to say, I don't think your dealing with magnetized balls, It sound like trough divots. The plastic trough insert is meant for that mostly. Marco has it and Pinbits has it also. Its about $7 US, $87 Canadian... Kidding.
You can test the switch with a multimeter. I think you put one lead to the middle lug and the other to the back lug and set it to ohms and then press the switch. SHould get a reading.

Ball_trough.jpg

Also, if the old balls are really beat up, I wouldn't use them at all. All pinballs ruin the playfield. They become like sandpaper. No good.

Question , do you have the machine nice and level, also is the trough angled enough? It should be on an decline towards the right lane shooter. Is it secured to the under side of the playfield good?

Here's another sort of dumb question but.... are the "new balls" 1 1/16 in size? If they are smaller or larger that might be the issue too. That's my last annoying question. I promise.

Yes, there are a bunch of different sizes believe it or not. I wouldn't be surprised if the new balls are slightly to small or larger than 1 1/16.
Do you have a micrometer to measure them?

I think most pins use the same size ball but you have pitch and bats that use a different size and strikes and spares uses a different size too if I remember correctly.
But if you checked them then they are good. Are they the mirror finish balls or standard finish?

The coil in the gun might be loose. Check the coil bracket and make sure its ok. Same thing happened to my JD ball shooter bracket. It ended up getting really loose. I tightened it back down and never had that problem again.

How did you make out? Everything working ok now?

Glad to hear you got mostly everything fixed. I would have never thought of the swapped wires either on the opto. Good lesson learned for that issue.
Btw, my buddy has a monopoly and I love it! Such a fun game. I couldn't get enough of it last time I was at his house. I really like the four player team feature 2 on 2 made for some very competitive pinball. Gl with the pf swap.