Thanks for accumulating and sharing this information. I recall when you started this, those many years ago.
Thank you for all the effort you've put into this, and all the speculation, detective work, and just plain adding up the numbers (and Saturn's rings). The mystery to me is what happened between the issuing of the patent (1903) and the production of "regular" Orpheum banjos.
Our goal was to document Rettberg & Lange Orpheum banjos and distinguish them from Lange made Orpheums because the change in ownership from R&L to Lange on January 1, 1921 gave us our initial benchmark date.Thereafter, we developed additional benchmarks from Rettberg & Lange history.