My 83 Schwinn is showing rust on the brake cable guides on the top tube, quite a bit of rust on the one farthest forward. I'm getting ready to replace the brake cables and want to treat the areas to prevent further damage. What do people use to remove spot rust and prevent it coming back? The bike has its original black paint. It's not a restoration project but it is my ride and I want to keep it in as good a shape as I can.