Quoted from ForceFlow:I've read that a few people have had success with this polishing kit for taking care of cloudy mylar:
amazon.com link »
I won't remove mylar unless absolutely necessary--it's too much of a pain, and carries some risk of lifting paint. It did its job in protecting the playfield, and it really doesn't affect play all that significantly. Clean it and wax it, and balls travel over it fine.
I also add mylar to protect from wear when I'm done shopping out a playfield. Most of the older games I work on don't have the benefit of those new protectors anyway.
I have full intentions on trying that on my phantom of the opera.
I typically will only remove the Mylar if it is peeling or discolored. I will put strips in front of drop banks and slings and also add Mylar circles to areas where the ball drops out of a ramp or from an upper playfield.