Attempting to comeback after 28 years away from the horn. Been at it for 4-5 months now. Low end is fine from bottom up to D in the staff. Having control and fatigue problems from E to G (G on top of the staff). Just fine from A to D above. Good days and bad above that. No real consistent strength (or confidence) in that mid range E to G area. Many times will start out OK there, but by the time I'm fully warmed up and comfortable (15 minutes or so) that area starts to be a problem. Still not pleased with endurance overall. A good practice session is 45 minutes at best. Don't feel like I am attempting to shift the embouchure in that range...just lose precision, control and tone there. More beer?