Ok,the book says how to make new curtains. I'll look tomorrow, you can read all you need online for shutter repairs of this type, and if you have the old curtain that acts as your pattern. I can't remember the Author or I'd find the link easily

My Thornton Pickard shutter was dry andvery cracked and dead so I used Methylated spirits to remove the old shellac or whatever it was coated with then ironed the curtains flat before using dilute Black PVA fabric paint to re-lightproof the curtain, it's very flexible, I did the same for my Speed Graphic which had a lot of pin-holes.