andrew:

that's what i thought. a lot of it is in your hamstring, but i don't think you can adequately use your front hammy unless your hips are spot-on. when i first got it (and lost it shortly thereafter), i think a lot of it had to do with just how spot-on your hips are. maybe even turn past square to the point that, you're turned off to the right a little when your right leg is forward in jin ma.

keep in mind that i haven't been able to duplicate this with any regularity, as finding that sweet spot happened once in a blue moon. however, when you find it, spend the next 15 hours drilling it so your legs won't forget it even if your mind does. it'll be worth it, and i'll be jealous.