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Somewhere I've posted a link to repairing shutters like this. My laptop died 2 weeks ago and I'm not straight yet but I have saved not only the links but the pages as well (from a partial PDF - not savable/downloadable).
It's relatively easy to make a new curtain there's patterns in the book, not sure if it covers the Houghton sgutters, it should.
These shutters work in two ways:
1. A single curtain made up of a number of slits, you wind the right bit into position. Graflex's etc
2. A pair of curtains so more complex. Moving seperately like modern cloth SLR shutters.
It could be yours is the first and has just come unglued/sewn. I've rebuilt a Graflex and also a Thrnton Pickard shutter neither was difficult. I'll see what I can find tomorrow, it's late here now