@juan, thanks for the info!
About the lens aperture / shutter connection: so you're saying that the "nipple" should actually just push on the aperture lever at the point marked in yellow in the pic below?
If so, it's kinda strange, why is the lever (green outlined) shaped like it is and why is there a hole it it?
It happy to believe you, but the design of the lever makes me wonder.
The point being, if the nipple goes in the hole, that gives a slightly different aperture from if it pushes on the lever!