Repairing a Vario Switar 86mm Zoom

[Graham Ellard]

We've been given a Vario Switar 86mm Zoom. Cosmetically it doesn't look great, and the aperture and focus were very stiff. Having dismantled it, cleaned it and begun to reassemble it I'm really puzzled by one of the parts. I haven't been able to find any references or images online that tell me what it is or what its function is. It looks as if it has been machined and modified in some way, like a customisation.

Plus, having very carefully reassembled the iris assembly and don't understand how the aperture ring engages with with the iris assembly. The ring runs smoothly but is not connected to the iris assembly 'tube' in anyway, and I can't see how it can be. Maybe there was a missing part originally, maybe the mystery part has something to do with it. I'm baffled, and would wlecome any thoughts, suggestions, or advice.

Here are some pictures that show the part in place, separately and the iris assembly in place, with and without the mystery part.

Thanks!