Is the bobbin case standard CB 15 or something else? 60 years ago the machine could have been made in Japan too. Singer had factories all over the world at one point, and it sort of gave off spring to local production many places. I guess the machine was made for the Japanese or perhaps Chinese (Taiwan?) marked. Maybe it's possible to find someone who can read the writing on the machine; there shoudl be a red herring to follow. I can't tell the difference with signs like this.