Rapax shutter + flash sync issue

Hi there, I have an old Rapax shutter (made by Wollensak according to the inscription on it) that I use for an equally old 135mm/f4.7 Wollensak Raptar lens. The shutter has a flash sync switch with the following options: M (black) - M (red) - FX - Off. See attached pic

Everything was working perfectly fine until I changed the flash sync switch from F-X to M. After that it seemed like the shutter only worked if the flash sync was on one of the two "M" modes, now it just stopped working altogether (can't cock it, and the aperture is stuck half open).

I've opened a couple of shutters before (including this one) and managed to successfully clean them up, and disassemble/reassemble them to some degree so I don't mind opening it up to take a look, but I'm wondering if anyone would have a clue as to what I should be looking out for? Is there something that's likely to break/disengage/whatever by changing the flash sync mode, that could explain this?

Any help would be appreciated!

Update: Well, I went a head and opened it up to take an initial look and... yeah. There's a loose piece in there, that can't be good... I attached a pic, the yellow arrow is pointing at the piece in question. Worst thing is; I don't really care about flash sync for this shutter so I'd be fine just bypassing the whole thing completely. Guess I'll have to try to find a repair manual and see what's up.

You might contact Bill at AlphaxBetax.com. He works on those Wollensak shutters and might be able to help with this.

Well, here's a completely unexpected update; I found the repair manual for these shutter. Turns out the loose part is the syncronizer's lock lever. It's attached to the synchronizer sub assembly by a tiny screw. The screw was also loose (which explains why the lever wasn't attached anymore), and was blocking another part of the mechanism, preventing the shutter to close properly. I removed both the lock lever and the screw, and the shutter is back working just fine! I assume flash synchronization is now officially dead, but as long as I leave it in "Off" mode, everything appears to be working just fine! To say I didn't expect this outcome is putting it lightly...

If you have the screw, replacing it and the spring might fix you up.

BrianShaw said:

If you have the screw, replacing it and the spring might fix you up.

View attachment 336957

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Oh! Good point, didn't even give it a second thought because I've never used a flash with that particular lens, but I did keep both the part and the tiny screw in a ziplock bag. If I'm ever in the mood for flash photography in the future I might actually give that a try! Thanks for the relevant diagram, much appreciated.