press the shutter release bar to roll the second curtain onto its take-up drum. put in the first curtain as shown here. Both curtains are now in the correct position. Close the bracket over the geared drums. Load each spring with four whole turns of tension.

Proceed by cocking (the noun is not allowed here) the shutter to see if there is enough overlap between the two curtains that no light shines through the slit. If there is a slit, loosen the springs, loosen the bracket over the geared drums, set those drums correctly and try again.

Put the cover over the shutter to see if it clears the whole frame. If the slit starts or ends within the frame, do the last adjustment again, this time turning both curtain's drums the same amount of teeth. When ready, put the bracket over the spring-loaded drums back in place.

Now lube the shutter mechanism. Don't forget the bottom side of the geared drums. Clean the inside of the camera and put the shutter back in place. Put the shutter release lever spring back by opening the Shutter on B and blocking it carefully.