[Yoda]

Heard Annika say that her main swing thought was to keep her right arm straight throughout the swing. Obviously it cant due to the left arms checkrein action. But that was her feel for extensor action and it obviously worked well.

Thanks for this quote, Daz. This is the essence of Extensor Action: While maintaining the Clubshaft On Plane, the right arm tries to stay straight, but can't!

The 'proof is in the pudding':

Since Annika's right arm/Elbow is very definitely bent at the Top of her Stroke, it must be the result of the Straight Left Arm's Checkrein Action (6-B-1-D) despite her Bent Right Arm's attempt to stay straight.