I got a few extra parts in a box from a garage sale and there is a plate that is 2 7/8 by 2 1/2. It looks a little different than the one you show and has a spring like clip on the back. If it is one you can use I would be glad to send it to you.
I wish I could find homes for the rest of the parts. I posted a picture of them sometime back.
Lynda