Pentacon Six curtain slips back and doesn't stay cocked

[unwantedfocus]

Hello,

finally finished my exams and have some time and wanted to repair the pentacon six. One screw fell out of the camera and suddenly it didn't work. when I advance the camera the mirror locks and in place and also fires, but the curtain does move back with the advance lever in its original position. Normally the curtain should stay cocked and not move back with the lever.

I have no idea were the screw came from I'm looking at the camera for a while now but can't seem to find it. I attached some images of the screw that fell out. Any help is appreciated.

 

[shutterfinger]

Download, read and follow the instructions. https://learncamerarepair.com/downloads/pdf/PENTACON-SIX-Service-Manual.pdf