Astair. Absolutely right. I would draw attention to the DVD by Slavic who teaches that in a Forward Locked position in the Cha ( latin cross ) Both knees are bent . Both heels off the floor . And the weight right in the middle. Knees touching . He then straightens the rear knee and leg to give a larger push out onto the next step which is to unlock. Very interesting. He does go into detail on this one. Cheers