I agree with contacting Fiskars, for advice. Years ago, my beloved pinking shears were getting hard to use, so I gave them a drop of (sewing machine) oil, up where blades joined. That turned out to be their undoing.
The oil apparently attracted more lint and before long, it was a major struggle to open/close them, at all. Sometimes what seems like the logical thing to do, can be the wrong thing to do.