If there is one main issue with TGM that drives me insane I believe it is this. Between Chuck, Yoda and Brian it seems they are each teaching a different way to grip and address the club. Brian teaches his "neutral" grip and a square face at address with mid-body hands. Chuck's has the hands at a "special" position and the face is slightly open (for a swinger). Now I'm seeing a mid-body hands and a closed face here. So which is it? Or is it another variation that the player can pick and choose which one works best?
For the record (Chuck), I go with the book. I’m not much familiar with other methods.
With a non-hand-manipulative swinger, centrifugal force will align the clubface for straight-away flight. Centrifugal force throws out the center of gravity of the secondary lever assembly; the sweetspot. Centrifugal force doesn’t know the difference between the clubface and your shoes. It only knows center of gravity. If you swing without having the center of gravity aligned (trailing and on-plane with the clubshaft during the downswing) then, unfortunately, centrifugal force will perform its magic trick without the bunny. And Bam! What ever part of the clubhead replaced the center of gravity during the downswing, will hit the ball. Normally, somewhere far away from the true sweetspot.
Take your grip in the impact fix location with the shaft leaning forward and with the left thumb and #3 pressure point on the aft side of the shaft (strong single action). Hint: (with your left thumb on the shaft at impact fix, it will seem to point toward the clubhead center of gravity). When your hands move back to standard address, turn your hands so that the clubface is square or slightly open. If you move your hands to adjusted address without turning your wrists, you have manipulated the clubface (TGM is about geometry, not positions). You will have to un-manipulate the clubface before the downswing because the normal amount of takeaway Turn and fanning will not align the clubhead center of gravity behind and on plane with the clubshaft for the downswing (at the top of the swing your clubface will be closed).
Non-hand-manipulation swinging means that at impact, centrifugal force will align the clubface. Before impact (and after), it’s just you.
Hint #2. The swing has 24 components, so learn these grips and alignments in Basic Motion, and then Acquired Motion so that most components are zeroed out or slowed down. Then you can see the effect of grip and alignment changes without an unknown other component interfering.