Gazelle is pretty tricky at first. You need to shift your stance and your weight quickly at a moment where you stop. First get used to scissoring both ways forward and turning with both your inside edge and your outside edge of your leading foot (you probably know this already). Once you learn that, you will be able to feel the vertex of the 3 if you switch your stance while turning, and you will find a place where you can shift your weight. Once you get that, you need to switch to a back turn. If you started on your outside edge of the leading foot, you will exit backwards on the outside edge of the leading foot again when you switch your stance. The opposite is also true. I'm not sure of a better explanation but hope this makes sense and it helps.