I'll throw one thing out there to ponder with this HUO debate. I bought a Space Invaders years ago that truly was HUO. Original bill of sale and all from the folks I bought it from. It had wear on the playfield in quite a few places...and here is why: they never changed out the original pinball.
It was more like a boulder in there rolling all over the playfield. And on top of that, they never waxed it. They liked pinball, but did not know how to take care of one. Their HUO Lethal Weapon 3 was in horrible shape.
Just something to think about.