Congratulations on getting a treadle and also for posting pictures. The decals are beautiful. Are you close to some place you can get a leather treadle belt and bobbin winder tire? There are several places to get them online, including sew-classic.
I'm thinking that your machine may be a
15K26 since the serial number indicates that it was made in Kilbowie. According to
http://ismacs.net/singer_sewing_mach...sses-1-99.html the 15k30 is an industrial model with Wheel feed and a roller presser. A resource for refurbishing various models of treadle sewing machines is
http://www.tfsr.org/publications/tec...achine_manual/ Lots of good information there. From my understanding, the 15K26 shortens or lengthen the stitch length differently from other 15 class machines. I found that info in the middle column on page 2 of this pdf --
http://www.tfsr.org/pub/technical_in...achine_top.pdf
Happy treadling
Janey - Neat people never make the exciting discoveries I do.