Super question... in the past, if I've been able to pull the cable out, I'll drench it with WD40 and clean with rag to get any rust and metal dust out of there and use something like lithium grease applied with a rag. That is in no way an approved method but it's just what I do and only if the cable can be removed from the housing. I can't remember if I've done that with my RS 200 though.
Orion