@Hillhouse sells (used to sell?) a flap called the Perfect Circle that can be a good tool. Jason Snyder's Pitch Squeak has become very popular and is very adjustable for different parts of the arm: https://www.facebook.com/p/PitchSqueak-100085035953780/This photo is super helpful!!! Thank You!
Looking at this it appears she has decent upper arm brush- but a little too much elbow bend so is missing lower arm brush- there’s a gap between her forearm and thigh - and she’s whipping around in that space rather than forward through it.
I really appreciate you taking the time to show me these visuals and drills.