Wow. 20 years?

That's quite a story... curious, how did you find the slam tilt issue? Just visual identification?

That reminds me of the gilligans island machine I bought. The owner got it for his 40th birthday.
When I bought it he was 57, so 17 years he had it. He said that he had been playing it a lot, and loved the game. Judging by the wear on the chest insert, and the pitted balls I could tell.
He had never done anything to the game, he didn’t know how to remove the glass.
The whole motor assembly to the island was gone. That means, the island would never turn. You would never get the ramp down for jungle run. Not for kona either.
In other words, all you played for never worked. 17 years! Insane.

That, right there, speaks volumes about what 99.9% of people that step up to a game understand. Basically nothing. Which is modern pinball's inherent flaw!

Yes! When people are playing in my pizzerias I always try to give them tips for simple things like multiball and basic rules, without coming across like a know it all... which I am not. The more you learn about pinball the more fun it gets!

This reminds me of the Gladiators I picked up. The man who had it was selling/repairing it for a friend. He said it had issues; balls would get stuck on the playfield and the GI didn't work. I picked it up at a great price.
He had 3 balls installed, not the required 4.
The GI was simply completely burnt out bulbs.

I always find it rarely - if ever - goes well

It depends on the repetition of which I hear them mashing the flippers. If they are just pounding them, no point.

I have had mine for 19 years. Ball was probably stuck somewhere in the playfield.

Different non Pinball similarity.
Friend had a 1967 Mustang for 7 or 10 years. One day he asks my opinion of his ride. I stated, that the Tilt Steering was not a common option. He said, "The What?". He didn't even know.