Over the course of my first year in college I was having problems in the upper register. I had a solid high Bb, but B and C were very thin sounding and working on range exercises proved to yield very little or no effect. One of the other brass teachers at my school noticed that as I ascended into the upper register my mouthpiece would move up my face until it was touching the bottom of my nose, effectively capping my range at a high C. I've been working on keeping the mouthpiece down and I have seen some improvement. Has anyone else had this problem and if so do you have any recommendations? I've been primarily working on scales and lip slurs and have started extending it to larger intervals. Any help is much appreciated.