It works the same as white spirit. It is citrus based and doesnt damage paint. Lift a corner of the mylar and let it run underneath with the assistance of gravity. It dissolves the glue very quickly. As long as the paint is still stuck to the playfield and not the mylar it won't lift. I put the smallest amount of pressure on the mylar and it comes away easily. If the paint is not bound to the playfield well, no method will save you. It might be worth following some of the other advice about polishing the mylar if you are like me and can't do playfield touchups.
