Are you balanced and centered over your board? I recently discovered and corrected some chatter during heelside turns while riding switch on steeper terrain. I fixed it by riding with my body a little further downhill than before. I really didn't think I was leaning up the hill. I'm an instructor, I don't lean uphill. Beginners do that. Well, I was doing it too. I also had some icy conditions show me that I lean into my turns more than I thought.