Quoted from CrazyLevi:

I know it seems discouraging but pinball machines break, even new ones, and it's just part of the hobby.
Part of the problem is the relatively rapid evolution of pinball from a commercial interest to a serious civilian hobby, which in the scheme of things, happened overnight. Even 10, 12 years ago pinball was primarily a route interest, with a collection of weirdos on the periphery who collected these for their home and took care of them without the expectation that they'd run for years trouble-free.
It's kind of like if toasters had spent 70 years as something you only saw in industrial kitchens, and suddenly they became a fad for people at home. And toasters were way more complicated and broke a lot.
I don't really know what to suggest, beyond you should sell/trade in the games that are causing you trouble and keep the ones that aren't. Or get out of the hobby if the occaisional service episode is something you can't deal with. As you are learning pinball machines are gonna go down, it's just what they do. Usually it's something simple but sometimes it's worse.
Fact is, (based on your listed collection) if you have 7 pinball machines in your basement and 5 of them are running, you should be pretty happy! When you only have 1 and you can't keep it working, that's where depression really sets in.