I have a acquired a 3M but found the shutter curtain to be sticky looked on the site and saw how to do it but on looking the screw for the second curtain is broken. I have a donor 3M to use for spares but do not know how to, anyone know where I can get a repair manual or how to do it
Yes it is the top of the screw that has half the top of the screw broken off so can not use. It looks like someone tried to fix it and broke the top off and there appears to be no tension on the second curtain
Maybe the spring inside is broken, which is common while over tightening the curtains...
Dismounting is similar to a Leica III except for the slow speeds mechanism, that is in the top of the camera around the speed selector. You can find a service manual for a Leica III for free easily on internet.
Its a fairly complicated job. Basically you need to swap the bushing sleeve complete with spring from the old camera to the new one. This involves dissasembling the camera so you can extract the sleeve and unglue the shutter ribbon from it. At least you have an old camera to experiment on! The sleeve is then installed in the other camera, the ribbons glued on and the shutter retensioned - should only be three or four turns. Isaak Maizenberg 'All you need to know about design and repair of Russian cameras' has all the details.