Intonation problems

Hi all,

I was wondering if there is a good way to tell if intonation problems on a bari are due to the player or the instrument. I have some problems with my True Tone stencil on the notes G#,A,Bb, and B in both octaves, as well as high D,Eb,E, and F. Most of the other notes are spot on. Is this an embouchure problem, or do I need someone to take a look at it? The G in both octaves is absolutely spot on, but just above it I seem to have major issues going too flat, and in the very upper notes going waaaaay too sharp, to the point where I can't lip it down. I've tried a good number of mouthpieces and reeds, but haven't had much luck.

One thing to consider is the fact that the neck is not original; I believe it's from a Bundy. Without an original neck, I can't tell if this is the problem or if the problem is with me or the sax. Would having someone else play it be a good idea? Thanks very much!

Jim