Having trouble being consistent on palm key notes, my teacher told me he sees me closing off my chin when I go for them. I could not feel this at all, and had no idea what he must be seeing. I tried at my lesson to not close off, but no difference. During the next week though, I tried hard to think openness in the chin area, and after many tries, when I was going for a high note,...oh wow! It actually worked. Sometimes we maybe can't feel the sensation of what's happening when we have an ingrained habit, and our subconscious has to work on it theoretically for awhile with the better info from a teacher before we can fix it. Anyway, my high notes are now 90% more reliable, more resonant and able to be controlled by a bend or dynamic contrast. In the course of a week-and-a-half! (well, I've also been at the horn for 8 years, 2 years with a teacher). Hurray for teachers! Without them, we could stay stuck a long, long time. Mine keeps systematically solving problems for me and anyone who listens to me.