Arrgghh! I keep breaking Topspin CF when stringing on my SP Swing. I think the string is being weakened where it goes into the string gripper. Once, it removed from the gripper, there's still a fairly sharp bend in the string that doesn't want to go away and makes it hard to feed through the grommets. On tensioning the next main through one of those angled corner grommets, it cleanly popped. I love poly, I just need to figure out how to efficiently string it on my machine. Any advice on how to avoid this problem?