Attached is a labeled picture of a typical AE dial parts under the number plate. Also attached are drawings of a typical A.E. dial showing the proper names for the various parts.
Click the picture for an enlarged view.
How to remove the number card retainer ring is described well in this topic and at this link:
http://www.classicrotaryphones.com/forum/index.php?topic=5833.msg70508#msg70508
http://www.telephonecollectors.info/index.php?option=com_docman&task=doc_details&Itemid=2&gid=1921
Jeff Lamb