More information on the Business Phonographs can be found in Frow's 1994 "Edison Cylinder Phonograph Companion" beginning on page 326. These machines were first described in the April and May 1903 issues of the "Edison Phonograph Monthly," and referred to as "Commercial Phonographs." I'm puzzled by the reference to a 2-spring motor, as mine (No.3526) has a "Home" motor in a special frame. It's not stamped "A" or "B", and retains the endgate and the May 22. 1906 patent date. George Paul