That gear? Lift it up. Now rotate 20-30 degrees clockwise. There is a tab sticking dow off of the edge, and that tab needs to be on the other side of the tab, the right side of the tab, coming up from the metal plate.
While you have the gear out, make certain that there is actually the main spring installed under the gear.
When the cocking arm is installed and is sitting in the most rleaxed position, the last gear teeth on the arm and the last gear teeth on the gear should be aligned...
Well, this is what I guess looking at photos that, to be honest, aren't the clearest. Wild shot in the dark. I'm assuming that there IS a main spring in there properly installed.
San Francisco, huh? Now I'm nervous. This wasn't me, was it? Care to name names? Synchro-compurs are pretty standard shutters, and to miss twice is a surprise. We all can make mistakes, but usually not the same one twice in a row.
It's hard to verbalize the position of the gears, the spring, etc. Search and download the Compur repair manual. You are looking for a #00 1100-xxx as I remember. Your shutter doesn't have the self-timer mechanism inside, so don't be fooled by that.
The lower arrow points to the leg of the spring sticking down and going into a hole in the gray metal part. The upper arrow points to a leg of the spring going sideways and sitting in a small slot in that part which is obvious I hope because I don't know how to describe it.
Be gentle if you need to reinstall the spring. Put the bottom leg in place. Now rotate the upper leg clockwise and slip it into the slot. I've broken that metal part once by aplying too much side force when trying to get the spring to sit.
What the heck- here's the cocking arm and that gear in proper position. See how the gear tab nests to the right side of the gray metal part's tab. Well, maybe your photo is just from it rotating the other way, as it can do easily. The gear is not directly under spring pressure; it pushes the gray metal piece whch is under pressure.
