I've seen curtains with marks of paint to repair the light leaks. The rest of the rubber on the curtains will not last forever, the liquids in the paint solve some rubber as well when painting.
The rubber on the curtains dries out when the camera hasn't been used for a long while. Repainting some leaks would only solve the problem temporarily when the other vulcanite is in weak condition.
Maybe some new fresh curtains is a better option, just try the yellow pages. With some luck there might be a repair shop around which can replace them.
Greetings, 🙂