This ornament is the only one of the four corners still there, though it is broken and loose, held on by the nails that the composition was anchored too. Sometimes I can get the ornament back in position but this one was stubborn. In the next photo, below, I've removed the broken part so I can clean the fracture and remove the nails.
These last three photos show the back. For reinforcement, and to replace the now missing nails, I cut some slots using a saw blade in a Foredom tool, (a fancier Dremel tool) Thin welding rod will be cut, and glued into the slots, cyanacrylate, both to glue the ornament and the rods. The next photos show masking tape in the perforations of the ornament, and the the slots and lacunae being filled. I'm using catalyzed polyester resin, more commonly called Bondo as the fill material.
Once that is cleaned up I'll do what repairs are needed to the face so I have a corner to make a mold from. The next photo shows the top of the ornament with its undercut. This would have been cast separately, as will the replacement ornaments.
The last photo shows the top of the ornament ready to be molded, with a plastilina dam surrounding it.