Not that I am aware of, unless it is part of that particular dish design.is there is any advantage to the square headed bolts the dish came with, versus regular 6 sided bolts?
I pretty much just figured I'd seal it up and take a chance - so I did. There was no damage to the box and the missing piece was not in the box at all. There was a very small fragment that was inside when I took the cover off to wire it up. It works fine, so I'll see if I can just get a new cover piece.