Sorry to hear this Greg. It must be so frustrating. A few years ago I had to have minor surgery right on the placement spot of the mouthpiece. It was no playing for three months and then back to the beginning with a ton off patience. Thankfully I am not dependent on playing for my livelihood.
I posted back in November that I had gone back to the beginning again. That worked fine and then the Ultimate level came out. I would some days get the Ab and somedays nowhere near. I could still feel I was not quite there so went back again through the early stuff making copious notes along the way and doing each exercise as if I was a beginner. This has been equally frustrating some days, but even having been through it a few times there were still things I had missed. The emphasis on the instrument playing you was one example. After a couple of weeks of this I have got to Allegro F and today that was as it should be. I have done a fresh set of PPCs and been meticulous about process and results, sometimes contrasting the two approaches. Last week I was playing duets and felt myself control pitch with the aperture corners in a normal playing situation. This is a first and different to whatever I have been doing for the past 50 years+(with 20 year break).Trying to do to all the progress exercises with slurs and tongue each day leaves me with the face muscles feeling as if they have been through a tough workout. This is also a recent development and left me so stiff on Tuesday I could hardly play as I was so comfortable on Monday I was stretching myself in the repertoire beyond my normal limitations. Yesterday was easier and today was flying. Learning to back off rather than blow harder makes a big difference in the upper register but playing louder is a point of conflict and the chops sometimes cannot sustain the volume in what is effectively a new embouchure. The key thing is everything is better when I get to band. I am totally focused on opening the throat. I feel that is me achilles heel, putting my foot in my mouth!!
One point on breathing. In my singing I was taught the silent breath by someone who is now one of London’s leading singing teachers. This really works as the air can only go to one place, it opens the throat and you fill up from the bottom of the lungs like a balloon. When doing the backswing you consciously make a sound. The silent breath is slow and good for preparation and is equivalent to the BCH. I find it very relaxing. When experimenting I find making a noise fills the chest but I am less aware of being full from below. I would be interested to know your thoughts about this. It contrasts with one former trumpet teacher where a lot of my breathing was through the nose in order not to disturb the embouchure.

Good luck with the recovery and thanks for the tremendous effort you are contributing to helping us frustrated players. When writing the notes I began to appreciate what an enormous achievement this course is with so many videos presenting such clearly thought out ideas.
Paul

Hey Paul, thanks for the great post. I wish I could get everyone to understand that going back to the start is the way to go to embed and refine the new habits!!! Yes, it is a huge amount of work but I totally love it and posts like yours make it all worthwhile, thanks!