I was tightening the loose arm on the bottom of the timing shaft when the screw gave way. It turns out that the black shaft is nothing more than soft brass; I overtightened and stripped the thread. I would have to re-machine a new shaft to replace it. What a shame, this was one pretty #4. It is now available for parts if anyone wants it. Send me an email.

The other thing I learned is why the shutter is faster going in one direction than the other. It is because the arm on the bottom of the timing shaft (that presses down the spring inside) is not centered square between the springs in the neutral position; it is off to one side. As a result, when you set the shutter to one side it will press down more than if you set it to the other side.

BTW: Centering the shaft and tightening the screw on the bottom does not work!