I am trying to remove the apron from a Gottlieb Atlantis in order to do some playfield restoration. I've removed the two screws at the back. It seems like I should be able to gently lift the back of the apron and slide the apron forward to get it off the tabs at the other end. However, it's just not moving -- it seems to be fixed to something I can't see. There is no obvious varnish binding the front to the playfield.
Is there a trick to removing these aprons? Am I missing a third screw site?