There were several Japanese companies that sold machines and from what I've seen some have "cross-over" badged names. Toyota, Happy, Brother, Kayo, Sanshin, Soryu and I think a few others that have been identified. I don't know when they stopped putting JA and/or C numbers on them. It has been suggested that the JA numbers are for the company that assembled them and JC numbers are for which company cast the head.
There was an article about the Japanese sewing machine industry but I'm not sure how accurate it ism which can be found at
https://www.scribd.com/document/3786...ustry-in-japan
There is a list that has been compiled with some of the manufacturers and badge names at
http://www.doubleveil.net/zssmp/resources.htm (you may have to scroll to near the bottom of that page)
Some of the Emdeko machines have different JA or JC numbers which haven't been verified as being made by Soyru.
Janey - Neat people never make the exciting discoveries I do.