Because I'm a tinkerer and can't help picking at things I did the following. The security pass insert has been raised and figured the artwork would have lifted with it (no brainer!!). So I was very concerned 1. its gonna lift and 2. this decal is not easy to find (if not near impossible).
So I picked at the mylar where it had lifted on the playfield and thought I'd see how easy it peeled. No crap, it peeled like a sticker. So I kept going, very slowly, a couple of fingers to steady the hand that's peeling and fingers on the other hand pressing on the playfield right next to where the mylar was peeling off. I hoped this would add a bit of stability to the artwork, decals and lessen the chance of lifting them. My eyes covering endless areas of the playfield as I progressed to spot any artwork lifting.
So here are a couple of shots of this process. It was slow but basically no gum residue (a bonus). I removed probably 70% until I felt too much resistence for my liking. BTW I freehanded the mylar off the security pass insert without a problem.