Mylar (80s 90s pinball) or Contact (70's 80s Pinball) were laughed at in the old days. My old man was laying contact on playfields in 1977. What was left was used on our school books ! People thought he was CRAZY removing NIB KISS, Paragon etc etc and laying the contact.
I removed the contact on the Paragon in 2004-5. PRISTINE playfield underneath. As far as preservation is concerned - Contact was king. I don't know how many machines I've removed contact from, but I know I only caused an issue with my Playboy - too much paint lift due to a lack of patience.
The cause of it to lift is usually the ball traveling along a crease - where the contact is trimmed. Sometimes it is the heat from a playfield globe or an accident while cleaning the game en route. Contact was not designed to protect a playfield, and the cheaper stuff shrunk with time. If it is put on properly, and trimmed around the posts prior to installing the posts, then it will not move.
If you are happy with your machine and the condition of the mylar - leave it - it is not a job for the faint of heart.
hope that helps
