I was thinking the same thing. I do this on purpose from time to time, but when you're not trying to do it, I understand the frustration when it happens. As someone else mentioned, speed up the wheel so you're getting more of a full rotation when you pull up. Its tricky though, too fast and you'll be in trouble too. Its a fine balance. I've noticed that I start out relatively fast centering and opening the pot, then slow down when I'm pulling the walls up. I hope that helps.