Thanks for the great advice, everyone! As it happened, I had an old Mamiya Sekor 35mm SLR laying around that was unsuitable for repair, so it gave one of its shutter curtains to the cause.

Now, after the repair has been made, I still have one corner at the top where there is a small light leak. I have seen references to using acrylic paint to patch little holes; is there a particular brand or type to use? And what is the best way to go about applying it?

Thanks so much again!