I have a Frigidaire Affinity. I just noticed that there is black gunk stuck inside the ridges of the door gasket. I had been innocently wiping the gasket with sanitizer sheets thinking I was keeping mold under control. This is deep inside the fold and doesn’t wipe off. (It doesn’t smell like mold nor does it get on my clothes) ) It is stuck on and crusty. I can scrape it off with my fingernail but I don’t want to. Is there an "easy" way or special product I can use to get rid of it?