Make sure the up post on the right side is level with the playfield? The ball can rest at either up post, so it can roll out the right side too, mine is a little slow when it is caught at the right post and releases, but a hitting a flipper is always enough to get it going.
I have no crumpling or issues with the mylar there though, sounds like you might need to remove the piece that's there and reapply if the ball hangs on that...