Here's the latest: I determined that the GG is set within the aluminum parallax frame (it's about 5" x 4.75") You have to epoxy one edge of the GG --on the pulley mechanism side-- to the frame, while the other side just rides on its rail. You have to be careful because the aluminum deforms easily. I used Devcon highest-strength epoxy and let it set overnight.

Unfortunately, when I field tested the camera, the taking and focusing lenses didn't jibe. Arrrgh.