I gather that your mother's machine is a zig-zag machine. I have many machines, including some Kenmores. I don't know of any of the high shank machines that use a nut for a presser foot. I can't remember which machine had some tiny nuts that attached somewhere in the bottom of the machine.
I have never ordered from this business, but there is a high shank zipper foot at
https://www.sewingpartsonline.com/zi...ank-55501.aspx
I don't know where your mother lives and if there would be a sewing machine repair shop in her area. Unfortunately, there are a lot of businesses out there that don't know about repairing or servicing vintage machines. Sewing machine repair shops are getting fewer and fewer.
Janey - Neat people never make the exciting discoveries I do.
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