I thought I'd post this in case anyone else out there is having similar or related issues. Quick background: played trumpet in high school, university music major (bass trombone); last played tenor trb & euphonium 10 years ago; now a comeback player on trumpet since 20 months; practice 60-90mins/night; playing in swing big band & concert band. (1) I've always had embouchure issues. In high school the chops seemed to obviously pull to the right side, almost laterally pulling apart the buzz - don't ask me why. Range was limited to a poor G at the top of the staff. Coming back to trumpet I strive to practice consistently, correctly and intelligently. Learned through rapid trial & error what efficient playing was about. Don't use excess pressure. Still learning to optimize my air delivery. Started on 1/2 & 1/2 mp placement and have settled on 1/3 upper. Have adjusted mouthpieces only within a small range (Schilke 10-12). Until recently was still plagued by an unbalanced set of chops, especially ascending, still pulling left (if I was a car I'd need a wheel alignment). Have not wanted to get overly analytical - have seen enough paralysis thru analysis. Then closer inspection showed that for some reason my lower jaw was shifting to the right even as I'd set the mouthpiece on my chops. Why? I have no idea. One side stronger than the other? Forceps-assisted delivery? Dunno. A slight and deliberate shift to the left (several millimetres, no more) produced immediate, dramatic and lasting results: a fatter more resonant sound, greater efficiency per energy input, far greater endurance, modestly better range (it'll come), a more even sound from bottom to top, more resonant lower register, and greater flexibility. I played a 3-hour big band show yesterday afternoon, had tons of reserve left over and practiced last night as well. Yah, I'll have to do a bit of chops re-training until the new position feels 'normal', but I'm obviously happy to do whatever it takes. Lesson learned: top & bottom lip alignment is critical to the aperture and air delivery. Misalignment of the top & bottom lips is very undesirable. (2) I've noticed that placing the right hand with the thumb between the leadpipe and bell, and the little finger well and truly in the pinky hook (but using very little pressure) was somehow pushing the horn to the left...resulting in greater mouthpiece pressure on the left side and an uneven mp seating. Positioning the right thumb between the 1st & 2nd valve casings and letting the little finger float free immediately had the horn pointing straight ahead, restored equal pressure to both sides of the mouthpiece, and seated it correctly. It's never felt this comfortable. Lesson learned: balanced lateral (side-to-side) pressure from the mouthpiece is also critical to the aperture and air delivery. For those of you who never had these issues, great. Just play! For those of you having issues, it's something else to check out. All I know is that it finally feels right, and sounds and feels great. Cheers!