If the mylar went down several years into operation and the field surface was already showing damage (and still does under the mylar) you are apt to lose a considerable amount of playfield ink. Just be aware that removing mylar from an already compromised older field can go really south really fast.

On Sys11 or older playfields, don't mess with the Mylar unless you are clearcoating the playfield.

I pulled mylar off of a Future Spa last night using a heat gun. It worked well, with minimal lifting of paint.

I agree with Vid. However I have an EBC that the mylar was very yellow and lifting. The mylar pealed off with ease but the adhesive stayed behind. I used goo gone on the adhesive letting it set for 15-30 minutes and pushing it off with those plastic razor blade scrapers. If you wet a paper towel with Naptha and wipe down the playfield anywhere the adhesive is it turns white. It took some time but the result was great. I had no intention of clearing that playfield because it just wasn't worth the cost. I did wax the crap out of it and recovered it with mylar and it looks awesome. Again agree with Vid but if its crap anyway its was worth a shot.