I have been told by a local Featherweight collecter that it is not a universal key. It depends on not only the year your machine was made, but the locks on the accompanying case are different. I did see a couple of different locks on the cases she had on display in her fabric shop. I am of the belief they have different locks and no universal key - hope this helps.

Thanks so much Budster.

I'm looking for information regarding the singer featherweight brass key (carrying case)....what years was the brass key available and for what models?