I found this, this morning and I thought that I would share it with the group. I found it on bestsewingmachinereviewed dot com. I think it will help explain our frustration in finding out who made a particular machine. This information would help Clone owners as well.
~G~
What about J-A numbers and J-C numbers? Forget it! This was a system used by the manufactures that used identifiers like J-Axx and J-Cxx stamped on the underside of some of these machines, but no official information on this system was released to the public. Some collectors and repair people have tried to create a database of these numbers, but the results are incomplete and not accurate. The reason is that most of the manufactures would do overload work for other manufactures so a certain model of machine may have been produced by more than one manufacturer and at several different factories.