I play a '57 Conn Naked lady Bflat. I took it to the tech to get some screw tightening and lubing of the lower keys. He also reseated some pads. When I play high A, I have trouble getting the note out clear. It's stuffy and it easily overblows to high E. It sounds much better when I play A without the octave key and lip it up to high A. It makes me think the problem is the octave key. I've looked and everything seems to be working properly. My high G is a bit stuffy but I have less problems. I play on #3 Vandoren reeds. Any suggestions?