Maybe its just your picture but I don't see the crap you are referring to.

And if everything is looking yellow, it may be old water based clear.

Take the glass off, and take a few more pics until you think we can see what you are seeing.
-mof

Test a small area with denatured alcohol. If it comes off, it is shellac. Otherwise, chemical solvents will dissolve any poly clear coats.

Mine's the same way. An operator swapped the playfield in the late 80's with a NOS playfield that he sprayed with clearcoat. Back then cc had linseed oil in it which eventually yellows. I need to strip mine off too.

If it is coated with real clear, then there is no way to remove it other than sanding, which you're not going to want to do. It is what it is, nothing you can do about it really. I'd just live with the yellowing if there is no wear anywhere to be honest.

Waterbased turns yellow, so does polyurethane.

There might be some chance of saving it if it is waterbased AND the underlying paint is in solid condition.

the Overlay is Un-Licensed .....

Nothing aginst the seller unless he is selling unlicenced material, but 400 for any overlay is a real bad Idea. They don't look good to start and they don't last long. pf's have wear, and all of the centaurs yellowed. its just the way they are.If you really hate it, buy a cpr pf that is bright white, and it is my opinion to get it cleared (for a bunch of reasons)
Just an opinion, everyone has them, and you asked. good luck, ron

ebay.com link: itm
What is up with the black circles around the bonus grid inserts? My 8 year old could do a better job.

I think the inserts are cut out of the overlay and what you're seeing is bad registration and...yes...hand drawn insert lettering.

ebay.com link: Centaur Pinball Machine Original Playfield With New Overlay

It is licensed if it is sold already applied to a factory Centaur pf. This is a restored playfield and not a new one. (although not neccesarily a very good restoration).

That being said overlays suck.

Ive seen a centaur overlay on person already and well they have the color of the the new centaur playfields but you see every imperfection under them so they look like crap. the playfield would need to be cleaned up cleared and leveled out before one could be installed anyway or the PF would need to be sanded down completely and releveled first. either way youde be better off just buying a new CPR.

I'd go with something like this. No way I'd pay $1200 for a repop. If Centaur is really a favorite of yours that you intend to keep, leave it alone, enjoy playing it, and keep your eyes peeled for a nicer one.

I just restored my centaur playfield and cleared it. Came out pretty good for my second PF restoration job, considering the damage that was done after cleaning it initially with ME and the flaky paint it had all over it. Not a bad idea to practice on some beater playfields. I did that for my first one on an absolutely destroyed Comet. It ended up much better, but far from perfect. But I learned a lot and that was the point.

https://pinside.com/pinball/forum/topic/centaur-playfield-clear-coat-mylar-removal-yes-or-no