Yep - rip it off and get a hardtop - do it right seal the playfield not just the inserts to make sure it has a clean surface and not just bare wood to stick too.
What you have is the problem with overlays and that is why no one real does them anymore if they have an hardtop option.
Of course a whole new playfield is better but that is huge work...if you have never done one before.
http://www.outsideedgeproducts.com/store/p75/Pinball_Playfield_Hardtop.html