In cleaning up my recently acquired 1914 Underwood No.5 (serial number: 674776)  I found another number stamped into the frame and carriage in two separate areas.  This number 797191 was stamped into the right front foot peg mount area as well as underneath the right carriage cover. 
Does anyone know what this other number represents?
I would also appreciate any information on how to remove the carriage assembly.
Thank you