Hi Group,  I asked the same question years ago.  Fred Dahlinger
contacted me and suggested the following:  Remove the cheek block on
the left side of the keyboard; turn it over and on the bottom you may
find the date, tuner's ID, and tuning pressures written in pencil.

I found it right where Fred said it would be.  He asked me to send
him a photo of the block.  It says "10/25/26, 1 p voice, 3/4 tune,
H A W".  Fred says that "HAW was an employee, "Doc" Whittemore."

Fred would appreciate learning your serial number and cheek block
information.   He keeps marvelous information on band organs and
calliopes.  My Tangley CA-43 is serial number 1244, manufactured
October 25, 1926.

Jack M. Conway
Los Angeles, California, USA