Supermatics are often greasy. Which will cause them to bind up, etc. You'll need to get this old grease out and add a small amount of new lube in the appropriate spots.
As to how hard this is, that's your call. If you haven't been inside a leaf shutter before, assume that you will be doing an autopsy, not a repair. You can try the lighter fluid flush system, but for Supermatics this will be a 5-step process because they can be pretty dirty. And there is no guarantee that it will work.