Hi Anne! I have a Singer treadle, sn#AA611881, also made in 1925. Mine is a 127, so I'm thinking yours probably is, too. I sent an email to Singer to find out. Here's a site with a manual:
http://sewing.about.com/gi/dynamic/o....htm?site=http://www.ismacs.net/singer/singerdates.html
Mine has the Sphynx decals. How about yours?