IMO, yo-yo'ers have a tendancy to throw too hard in the beggining. Especially seasoned, rock-star-type yo-yoers. I find the more aggressive you get with a rip-chord the more likely it binds or slips. I'd ease up on it and just practice the throw to the ground. Also, make the throw look as dorky as possible. Seriously. Arm straight out, no elbow movement, use your whole arm to push the top, stop your arm dead and simply let the top do it's thing. Add power and decrease the robotics later. Also, a tasty beverage helps.