You're in very good hands with Mopar-- he's more knowledgeable about this stuff than I am.

With regards to game selection, I assume you saw this old thread of mine, and that's why you PM'ed me (https://pinside.com/pinball/forum/topic/a-couple-of-shuffle-alley-questions). In the end, I never did remove that jumper (though I did solder it in rather than using alligator clips). I never could figure out why it wouldn't "lock into" a particular game, and the fix, while a little hacky, did work.

>the lock relay does not energize so this makes the game over coil drop out and the plate goes all the way to the rest bar, see picture.
I can dig out my schematic later, but if you happen to have a close up of this part of the schematic we may be able to work through this quickly. I'm not quite sure I understand from your description what is going on-- is one of the latches becoming unlatched when it shouldn't? Or is it not latching when it should?

With the pictures-- the lower picture, in the section that shows the start relay, extra shots relay and the lock relay-- we need to see the rest of that circuit-- I think you'll find the key to your problem there.

Or just solder them shut.

It's probably not worth enough to justify the cost of the parts, but if you *really* want to do it, there are new playfields out there... http://bayareaamusements.com/Merchant2/merchant.mvc?Screen=PROD&Product_Code=GS-SHUFLANE-UN

FWIW, I have a United machine too, and it has some of the white spotting you've got on yours. I cleaned it well when I first got it, and use liberal applications of the "cheese" and it's been just fine for me.

http://bayareaamusements.com/Merchant2/merchant.mvc?Screen=CTGY&Category_Code=BOWL

May cost more than the bowler, but there’s reproduction Formica out there.