At first you think the eye is missing, and then you realize that there aren't eight balls in the pit -- there are seven brightly coloured pit balls and one slightly larger whitish orb with a glinting glass lens. The other balls are stamped with the C.C. Catt logo -- his manaically grinning face.

There doesn't seem to be any obvious way to open the plexiglass cover. Maybe you can do something with the manual override.