I have brought some rubber seal parts on a car back to life. These were rubber, not weather strip, but rubber seals in a couple places around the window of an older car. The parts had some paint overspray on them. I took the part off and brushed a little aircraft paint stripper on them. Let them sit in a pie tin for a while. This is the nasty methylene chloride stuff that is gradually going away. Much to my surprise, not only did the paint come off, but the parts seemed much more pliable.