Just to pipe in....I sold this horn to habschi2. The key feet have individual adjusters for the stack keys, much like a Conn 30M. Easy to adjust. ***correction: the adjustors are lost motion adjusters so you can set the key height independently...I mis-spoke***I opened the key heights for personal preference as it matched the large bore older Link STM that I was using. The closer spacing worked with the included JK mouthpiece, which I seem to have misplaced or (likely) loaned to some student. It might be helpful (this to habschi2) if you provided more detail of your experience (mouthpiece type...high baffle, lg. chamber) and the problem (upper stack/register sharp or flat compared to lower), and relation to palm and bell keys.