If you are not pushing through your whole foot, you are losing power and balance. It is even worse if you tend to move your feet during the pull. If you have one of those problems, here is a simple fix!
Take a couple of plates, and stand on the with the heels off of the back. Then, complete a few pulls where you are forced to drive through the balls of your feet. Next, step back off the plates, and perform a full clean while being sure to push through the full foot!