Lesson

Had a great lesson from Gwen yesterday. You have to realise I am able to get 3 lessons twice a year from John Lassetter and then I am fortunate to have a few more inbetween the bi-annual Lassetter lessons. So to have a lesson was a gift. Everyone needs eyes on the ground.
Make sure the trot work in well forward. Shorten your reins. Keep your heel down and use your calf. Look up.
For 4th level what do you need? Collection and straightness. Yes, but to be successful what else? Suppleness.
Whats the best way to get suppleness? Shoulder-in ie. lateral work
Stair Step Exercise of shoulder-in to half pass. First at walk and then at trot. It is a good supplying and strengthening exercise for the horse and a good supplying exercise for the rider. The rider has to change from shoulder-in seat position to half-pass seat position. Be aware your shoulders to not block the horse when changing from SI to HP. Your shoulders follow the horses shoulders. The seat changes from weight on outside to weight on inside.
Now for the half pass. In the corner do a few steps SI and then focus on X and ride to X in HP. Gwen stood on X. "Look where you want to go, your looking at me and will run me over. I want you to go in front of me. Challenge yourself, slow down if you have to. More bend, shorter reins. Yes, now she is crossing." You can set out a cone at X and ride in front of it.
Canter work: We started cantering to the right. she was anticipating and pushing against my right leg being quite crooked. I'm not sure of my seat ins crooked or what but she has been doing this when she gets excited and I can not get her straight. "Go in shoulder-in or shoulder-for position." That way she has to step under and use her right hind. She was still pushing her R hind inside. "More bend right and suppleness as she is bracing against you, make her a little deeper to use the back." As soon as she was just a hair deeper she started to be more supple and straight. No longer pushing against the riders right leg, allowing a shoulder for position. When she does this you can never push her HQ over.
Medium trot: Yes, ask for more. Do short diagonals. That was the difference between a 5 and 8. Yes your concerned about the past R stifle injury but you need to strengthen it. Short periods. I don't practice mediums and extensions on Safarie often.
Counter-canter on the 20m circle. Don't use the outside rein, soften it.
She changed because you let you leg drop. That was a huge flying change which you can never punish her for. Start refining your flying change aids. Just let your leg drop. Keep the rest of your body passive. The second change was not as good because you gave the aids and your hands came up a bit. Good that was clean. Make sure the canter is forward, don't slow her down prior to the change.
Canter right: K-B and change in the middle. Then B-H and change in the middle. I felt my body was in the wrong position when on the second canter phase changing L to right and she was a little late behind. It a good exercise as you have to be balanced and you have to turn and then change. Also you are doing a second change in just a few strides, so organization and concentration.

On Safarie I practice his Passage and Piaffe daily as he needs strengthening and improvement. I do not practice the mediums/extensions in trot all the time nor the canter pirouettes.