Since the ball is constantly being dropped on the artwork it might have already separated from the playfield and the only thing holding it in place is the mylar. So when you remove to replace with a new piece the artwork might come up with it.
That's pretty common, but by the time it gets to that point you can hardly see the artwork for the clouded mylar and accumulated dust under it. So it's pretty much a given that you're going to be doing some touch-up or a scanned sticker.
I really love the Avery vinyl laminating sheet stuff, it gives some flexible strength to many things, including drop and lolipop targets (I often custom cut circles to adhere to the front of plain plastic circular and rectangle targets (cutting an extra small hole with a punch for the rivets to show through). My theory is that beside the constant abrasive pounding that the hard plastic targets get, the flexible vinyl helps distribute the impact a little with less chance of cracking the target.
Once you decide to remove the Avery Vinyl, the plastic below it is saved from wear and tear and you just apply a new piece. They remain flexible and adhere for a long time. I find that it doesn't edge peel as much as mylar does (which goes brittle with time), and adhesive doesn't ooze out the edges attracting solenoid dust as much as mylar does. But then I haven't been using it as long as some of the mylar that has been on most of my machines.
