I've got a vintage 6M in excellent condition but it doesn't play in tune. The top register is all off with the 4 highest notes being way way off. It's in terrific shape and I just had a very experienced tech look at it. He indicated that it is perfect mechanically and the only thing he could suggest is that the tuning issue could be related to the choice of mouthpiece. Current mouthpiece is a Selmer S80. Can anybody recommend another piece that might be easier to play in tune?