Quoted from Rarehero:
The Pinball Pal "removable" protectors are bullshit. They ruined my NGG playfield. They started to bubble over time, and when I tried to remove them, they pulled up the insert art. If you're gonna use mylar, just use real mylar and freeze it off if you need to down the road.
Did you use heat like with a hair drier and follow through with that Orange Power Cleaner/Degreaser Spray remover sold at pinrestore.com? I've had great success with this method (but not after going through the school of hard knocks regarding mylar removal).
I even use this method on Diamond Plate era playfields where supposedly the freeze spray method works great. But, sometimes the freeze method doesn't work great. Heat and the Orange Power Cleaner/Degreaser Spray remover (do not use Goo Gone - its not the same quality. Instant fail!).
And of clearly you cannot just simply pull off the "mylar" - whether its labelled "removable" or not.
I won't be so bold as to say removing mylar with freeze spray is "amateur hour". Its a novel idea and when it works it works great. Its a "possible" quick fix for Diamond Plated playfields.
But, if you want 100% success with zero art/paint loss, heat via a hair dryer and the Orange Power Cleaner/Degreaser Spray is the way to go. Use the heat, get a little lifting, spray the orange stuff under the part that's lifted. Apply more heat, lift a little more, spray more Orange remover, more heat, etc.... until the 'mylar' is removed. Then simply wipe away the rest of the glue residue.
Go slowly and take your time. Don't rush it.
Again, you will not have the same success with Goo Gone. I have not had success with that product. You need this (scroll down on the page):
Orange Power Cleaner/Degreaser Spray:
I've done a lot - and I mean a lot - of mylar removal playfields from the 1970s to the 2000s. The above method is the only one I have repeated 100% success without any (and when I say zero, I mean zero) artwork removal.
Heat, Orange Power Cleaner/Degreaser Spray, go SLOWLY == Success!
As Hans would say, "Hear me now and believe me later...".