My movement looks just like this one. The screw head for the stem retainer is missing...

Is it really missing? or am I missing something?

I can't get the movement out of the case if I can't figure out how to release the stem.

It's the whole just above the winding wheel.

I reckon I could relax the spring, remove the winding wheel and remove the bridge... but not sure if that is reversible going back together.

Paul, unscrew the case screw and three plate screws on the bridge barrel cover plate that holds down that crown wheel and the broken screw & stuff, etc., then lift up the plate and you should be able to see what the ? screw needs or remove it with a pin vise. (NOTE first let the mainspring down gently.) If it is a screw file a slot in the broken end of it.

Paul did you try to press/push like in some wrist watches?
just saying not sure if will work.

Dave, Thanks, That is where I was headed, just hoping it might be simpler than that.

Peter, that is the crazy thing... I thought it might be an "improvement" to a push pin style.. but it doesn't appear to be. I was shopping movements to buy for parts... and stumbled in to this example that looks exactly like mine. I won't know until I get it apart if it is actually a failed part or a design I just don't understand.

As it turns out, the watch runs fine and I returned it to the owner without taking it apart. He opted out of the risk/price... so, I will not know until the next one comes through.

I found one in my junk pile 18 jewels molina it's just like wrist watch you push the pin and the stem will come out.
Russians are crazy so it is improvement for sure to have push pin set not screw set .

Perfect, Thanks Peter... I must not have been lined up on it right.

you will have to press it hard as we are not use to to hard pressing on watches remember its made in USSR on Swiss.
SU mark on the watch = Soviet Union.