Quoted from swampfire:

Here's a cautionary tale, about how I turned a small problem into a really big one.
I noticed that my ring insert was separating on the right. I looked under the playfield and I could see that the glue was thin on that side (the side you can't see here).
Still okay
No problem, I thought - I'll just glue it down with some slow-setting CA glue. But I couldn't help myself. I just had to press it to see how loose it was on that side. Disaster struck: the insert popped out, and some of the clear and art on the "good" side broke away.
Noooooo
I've got it back in, and I can live with it for now (until I can get a new playfield):
Back in the saddle
The real tragedy here is that the rest of my playfield was still perfect. Shire, Gimli scoop - perfect.
What should have remained
Long story short, if you ever take off that LED PCB like I did, treat this insert like it's plutonium. I never should have pressed it from that side. Idiot.