Oops, My bad. Don’t know what I was thinking. After seeing the schematics I forgot the RS1 was air assist (It’s been so long since I’ve seen an RS1). Most likely the fork seals are bad but I would still replace the fork. Just make sure if you buy used you get a shock with the correct head tube length for your ride. You can always cut the head tube down, but ya can’t strech it 😆 😆 😆. As far as repairing your fork goes these guys are the pros on vintage forks. Here’s a link.
http://www.hippiesuspension.com/
Once again, hope this helps. 😃 😃 😃. Till next time be cool. Peace out!