This sewing machine was made in the 1950's and/or 1960's in Japan. It's a sturdy, heavy machine with metal gears inside--but since it's a Japanese clone, it's difficult to find the manual or track down a serial number. I'm posting this manual here for folks that are looking for it.
History note: After WWII, the United States helped Japan rebuild its industry by sharing patents--including patents for sewing machines. The Japanese "clones" were well-made sturdy machines, and many of them are still in use today. :)