I don't have a photo of it but it's got a spring clip that keeps it in place. Two protruding notches in the back of the cover slip under the rear lip and the spring at the front locks it in. Or as it the other way ? doesn't matter.
You don't really need the cover to lock into place since there's not really a lot of movement when raising or lower the head. I would just fashion something from a piece of aluminum or similar and bend down the sides a bit to keep it from sliding off. You could add some foam seals around it to control any light spill or spray some matte black paint on the underside.