I have never used a leader. However, I have learned a trick since the first quilting class I took. When you wind your bobbin, do so slowly. What I mean by that is not the fasted that you can wind it. If the fastest was 100%, if you wind it at a speed of 60-75%, you will probably never have issues with your bobbin thread again! I'm not kidding you! Since I relaxed my speed of winding, I've not had a problem! I'm going on ~8 years of no bobbin problems!