I clean all my seals with a rag wet with alcohol (denatured
). Then I go over them, inside out, with Aerospace 303 which helps rejuvenate the rubber. I have used a Dollar Store pledge type product and it worked when I ran out of 303 during travel. I don't think it soaks into the rubber like the 303 as best I could tell but it is much cheaper.
If you aren't having problems with the cable slides leave them alone. IMO you should keep an eye on the darco covered bottoms to make sure they are fraying or wearing and they're clean. Maybe once/twice a year I take a cloth, spray it with dry silicone lube and wipe over the cables for the slides.