I recently opened up the Rapax shutter for my 135mm Wollensak Raptar lens had gradually been slowing down to the point it would simply stick open at speeds slower than 1/25th to see what could be done, but seeing the the delay mechanism was not a discreet unit that could be easily removed thought better of going any further. Before I could get the face plate back on however a spring jumped loose and I have been unable to determine exactly how it goes back in. I was hoping someone who is more familiar with these things might be able to suggest how I might return it to its original position.

Here is the spring in question, the coil is about 4mm across.

Here is the rest of the shutter with the face plate off. The red arrow indicates a post that seems to have no purpose as it is and is just the right thing to be an anchor point for the coil of the spring, and it's also in the general area the spring jumped out from, so I'm assuming this is the starting point. I haven't been able to find how or what other part or parts it is supposed to give tension to.

To get a better sense of what the part might do I put everything back together without the spring and so far as I can tell the shutter still appears to work at the higher speeds. At lower speeds though it has the opposite of the original problem as they are obviously too fast. One second sounds more like 1/8 of a second. It still works on T, though if the shutter button isn't pressed and released very quickly when the shutter is opened it will close again. It doesn't work on B, though to be honest I'm not sure if it ever did.

(The shutter had flash sync contacts BTW which were removed many years ago and this didn't affect the workings of the rest of the shutter and I'm not concerned with that.)

Any suggestions, even if they're just highly educated guesses, about what this part does and how it can be returned to its original position would be appreciated.

Many thanks,