Here is the right side view of the same camera I have, there is a 1.25" long slot on top, behind the lens, and to the right of the center line (just above the Kodak logo). there is no metal key in it. There is the knob, on the right side, just in front of where the film cartridge would end when inserted, it has two settings. I do not know what this does, but it is right in front of where the shutter mechanism is located inside the film cartridge space. Could this knob be the filter mechanism? or is the slot on top the keyslot you were referring to? I don't think a screwdriver will fit into the slot.