Yoda, Brian seems to have good extensor action during his swing but at one point at address you said " straighten that left arm" or something like that. Is this trying to use the extensor action of right arm from the adjusted address position to straighten the left arm?
I think I have read one of your posts where you say that extensor action is one of your keys at adjusted address before your motion begins. Is this a key to help set your radius ? remove any slack in the left arm?
I hope that Brian's hard work pays off, it can not be easy looking for the breakthrough that allows you to reach your real potential. If TGM is to regain / attain its status as orthodox instruction it is going to take somebody like Brian to transform their game, then the "pop" golf instructors will see the light and the golfing masses will finally start to make a better swing rather than buy a bigger club! Good luck to you both!!
