Fitting issue on the Yashica-12 TLR

Dan Daniel said:

The spring at the blue arrow is out of position.

Where is the counter? That is integral to proper operation.

Click to expand...

Maybe hardly visible - but as written in the picture, I already began to disassemble everything in this picture - that's why the counter is already removed and also the springs detached. ( I forget to take a picture of this situation when everything was still assembled)

With this picture I just wanted to show what was the position of the winding stop lever arm and the brass thing on the rotary disc, when it is jammed.

Maybe It is better I make a video showing the inside from loaded to picture "1" to "jammed". Will need some days as I have a busy week.

OK. The right side of the board is where you need to pay attention. The two black lever parts and where they interesect affect the overall rotation of the winding lever. The lower black lever is moved by the shutter release at the bottom end, pin on back side of plate. Well, you'll get it.

HHS said:

Maybe hardly visible - but as written in the picture, I already began to disassemble everything in this picture - that's why the counter is already removed and also the springs detached. ( I forget to take a picture of this situation when everything was still assembled)

With this picture I just wanted to show what was the position of the winding stop lever arm and the brass thing on the rotary disc, when it is jammed.

Maybe It is better I make a video showing the inside from loaded to picture "1" to "jammed". Will need some days as I have a busy week.

Click to expand...

I think you need to reassemble it and start fresh. Once you dismantle the mechanism you have lost vital information regarding the interaction of parts. You need to make sure you understand what 'should' happen and then determine what is different in yours. Once you do that then you can dismantle it to try to find the root cause. It's basic fault finding techniques.

Note that the winding stopper only stops the crank from going clockwise (advancing the film) it won't stop it being wound backwards. You say the crank won't move either way so the problem is somewhere else.

Thank you very much, that's more than helpful @Dan Daniel and @monopix !
I think I have dismantled and reassembled it at least three times. And indeed I could find small things and fix/ adjust, so it is running smooth - except the named problem.
Today, I realised that my test conditions were inadequate and perhaps unrealistic: A completely empty plastic film spool, already somewhat worn out (you can see traces of the scanning wheel), naturally leads to errors, as the scanning wheel in the upper film chamber no longer runs correctly. A fully wound spool in the upper film chamber, on the other hand, sends a completely different signal to the mechanism – with similar results.

So I threaded a 6 cm wide and 30 cm long strip of thin paper into an empty film spool like real film and wound it up just as before. Surprise: this time everything worked without any problems. I was able to replicate this several times. Even simple adhesive tape wrapped around the spool at the side where the scanning wheel is running worked successfully. So in theory I should be able to use a fresh film without any problems now.

This helps me a lot to find out, if there is really a problem inside - or maybe outside the camera ;-).