Start with the right hand (spring) side of the shutter. Draw a line on the rubberised side of the cloth where the stitching was on the original shutter. Spread contact cement from here to the end of the shutter cloth. Also spread contact cement on the brass axle, taking care that you don't get too close to the ends. The sprung axle should be left in the casing for this.
Carefully wind the shutter onto the axle taking care that it remains parallel to the shutter casing. Leave the glue to set for 24 hours.
Repeat the process at the other end. It will be easiest if you take the entire axle assembly out for this step. If the axle has a balsa wood sleeve this hould be removed first, i.e. the shutter curtain is attached to the brass, not wood.
Replace the balsa wood sleeve if your shutter had one and put the axle back into the casing. If the string that cocks the shutter is broken this should be replaced now. There is a hole in the bottom of the pulley which is vaguely visible in the picture above. Thread the replacement string through the hole and tie a knot in it. You can hold it in place with a drop of glue but this probably isn't necessary.
Now wind most of the string onto the cog. The string runs through a little wire loop and then along a channel in the casing before exiting through a hole on the right hand side of the casing.
Carefully wind the shutter curtain onto the sprung axle. You will need to unscrew the spring stop at the top to allow the sprung axle to rotate freely. When you have taken up all the slack reassamble the gears on the top plate. Refer to the picture on page 2 for a rough guide to the correct orientation of the large cog. When you pull the string it should wind the curtain onto the left hand (unsprung) axle until the ratchet lever engages with a stop on the gear. At this point the shutter should be in the open position. If not simply change the orientation of the large cog a few teeth at a time until you get the correct position. If you then keep pulling the string it should wind until the second stop and the shutter should be closed again. Lifting the lever should allow the shutter to fire.
Here you can see the almost finished shutter. At this point you should try test firing it to see if the speed seems right. If it is running too slow you will need to disconnect the spring stop and wind the brass knob a few times to put more tension into the spring. This will be a trial and error process.
If you have access to a shutter tester to establish the speed you can then adjust the tension to match one of the marked speeds (these vary from model to model). Then by unscrewing the ratchet lever on the speed dial you can rotate the dial to the correct speed and then reattach the ratchet.
And here we are with the finished shutter, except that I am using a baffle borrowed from another shutter. I still need to make a new baffle, which will be cut from 3/8 inch MDF. The hole in the baffle will be the same size as the hole in the rear of the casing. The bottom of the baffle is rounded at both sides so it doesn't snag the curtain and the top left corner is notched to leave room for the loop that the string is threaded through. The end of the string has a paperclip tied to it temporarily, originally it would have had a small metal ring or a wooden bead.