Just to be clear, your playfield wood was already planked, like most System 11 games are to some degree. It's less noticeable under mylar, which is really the only protection those playfields had other than a thin lacquer which has broken apart by now. Just about any chemical you use on a playfield like that is going to make it worse.

I get it, 25+ year old bubbled up mylar can look ugly, but I think people need to lower their expectations when they decide to pull it and try to somehow "improve" the playfield. It's not like pulling mylar off a newer game with more modern finishes (DiamondPlate/clearcoat). With rare exception I just don't think it's worth the time/effort of pulling mylar on pre 90s pins, especially with all of the new playfield (or hardtop) options out there.

Sorry, just my $.02 from decades of experience and passing through a thread that had me curious