I'm retired and have been playing Tenor Horn for just over 3 years. About 18 months ago, I was moved from 2nd to 1st Horn. Recently, our Solo Horn player has had to stand down and I've been given the opportunity to fill the vacancy. Having tried this position for a couple of weeks, I'm finding the upper range quite tiring on the lips. Playing a high "G" is still a bit hit or miss and high "A" is totally unobtainable. My question is. How can I develop the upper range of notes? Is it practice, technique, or both? Would a change of mouthpiece help in this? I play a Besson Sovereign ( a Lottery one, I believe) and use a 2A Heritage mouthpiece after changing from a DW 3.