Welcome to the Quilting Board!
I think this is a 28, can't be totally sure of the 2nd digit in the serial number, looks to be in 1906 with a run of 225,000 numbers. Cute little machine in a nice looking treadle in the Dallas area in case anyone's interested.
I have a screw driver and YouTube--I can fix it!
I bought a red head in a treadle. The treadle has no pitman nor a screw to hold the skirt guard in place. The had converted it to a electric. I called a dealer where I get my old parts from to see if he had any for me. He told me that those things were just junk. He had no room to store junk and to try a junk dealer for those parts. I was horrified at his comment on just junk. Do any of you have any spare pitmans or screws that you would like to sell? Kathie