miriam

Many if not all Japanese machines have a J-A + number in the casting. This number Ids the manufacturer. As an example Happy used JA 10. Janome when they made New Homes used JA 2 & JA 30. Maruzen made Kenmores and used JA 4. The list is being compiled by on a Yahoo group by Bill Holman as information becomes available, but it isn't complete yet (maybe never will). The manufacturer of the JA 54 hasn't been identified yet.

More info:

From the mid 1970’s what are often referred to as ‘Nostalgia’ model 15’s were made in Taiwan and then later in China. These were made to the same design as earlier machines with the traditional black cast iron bodies and with the RAF or Sphinx decals etc. They were even supplied in the old style bentwood cases or treadle tables.The machines built at the Singer factory in Taiwan were identified by the model No. 15NL, whilst the Chinese ones are model 15CH. Although these machine look like the originals, there are subtle differences and they have a poor reputation of being lower quality machines that tend to be very noisy in use.

http://www.singersewinginfo.co.uk/15/

Quote copied from the above link. More information for your memory bank.