Quoted from dnapac:And 15 years ago pinball was dying...all but dead. All fixes by techs, or not, were nothing but a shot in the dark. I'll take pinball today vs. then. All advances in tech have their risk. Maybe it's forgotten, and the one who've bought into it are screwed (beta vs. VHS), but advance is better than dead. A risk into the advance is always a risk. A risk on an established company (Stern), is better than a risk of a new...but still a risk...but a better bet. Chose your poison. I choose advance vs. stagnant.
But there's no excuse for Stern to not release documentation and circuit diagrams.
I don't buy for a second that they're protecting trade secrets.
Documenting and codifying all this stuff takes time and effort. Time costs money. Stern don't like spending money on anything without direct financial benefit to themselves. Elimination of fuses should tell you all you need to know with regard to their attitude to costs.
JJP machines are way more complex, and they document EVERYTHING.