I'm rehabbing a new to me 1984 Trek 610. It has cosmetic issues I've been dealing with in the forms of scratches and some light rust. One thing I've never had a lot of luck with is dealing with rust in the top tube cable guides. That's a tough place to get to. Any good ideas?

I've used dremel tool in the past. It works but it will also take a lot of the paint out which I'm trying to avoid. I've got a really good match with touch up paint so I could deal with losing a lot of paint there but I'm hoping that someone here has a better system than this.