Amongst my grandmother's sewing goodies, I found this mysterious cylindrical solid steel rod and cannot figure out what it's for. She had an Elna Supermatic (ca. 1957) and multiple same era Singer's.
About this piece:
Approx 3" long
Approx 1/2" diameter
Solid metal piece
A single etched line about half way down
Etched marking "660-Y"
To be honest, I'm not certain it's even a sewing machine part, but I feel like if it is, it's related to thread -- like a thread guide of some sort.
Any help or guidance would be greatly appreciated!
https://photos.app.goo.gl/9ve3RmZFGXqMq5WS6
Thank you, kindly!