Lo, why don't you contact Jack Kanstul directly by sending him an email? His email address is to be found in his "profile" which you get to by clicking on his name in the Kanstul forum. I'm sure he'd be more than happy to answer any questions directly.
Another option is to get in touch with Priscilla King at King Music. Her website address is:
http://pickmusic.net/ . She is a trumpet player and teacher as well as store owner and representative for Kanstul and in addition to that, has played the ZeuG.