That means that a professional restorer either rewets the paint and fills in missing areas, or removes the craking paint and replaces it with new paint that keeps the same appearance. Choose restorers carefully. In the marketplace, restored cels seem to command the same price as original painted ones even though I would have thought that the original paint would command a premium. I do know that some collectors will not buy restored pieces, but in my experience it seems as though most collectors do not mind. I do not know of any help for a cel that has cracking to the actual image area.
Drawings are a little trickier.
I have never had a drawing be restored, but I do know that paper restorers do exist. Even though animation drawings are less expensive to collect, they do cost more to restore. At the end of the day, try to keep your art as safe and in as steady conditions as possible. But be happy that if problems do occur, then there are some solutions available. This article is copyrighted Debbie Weiss, and may not be reproduced in any form without my expressed prior consent.