Welcome, Mike. That is a nice looking machine. If you have a manual similar to the one available at
https://www.singer.com/support (
W1514 model number) I'm wondering if you are referring to what is referred to as "C" in that manual on page 12 of the pdf (pg. 11 of the manual). It appears very similar to the Singer 15-90 tension. The manual for the 15-90 can be found at
http://ismacs.net/singer_sewing_mach...odel-15-90.pdf On page 24 of that pdf it show how to remove and reassemble the tension. Perhaps that will help.
Also, could we get a picture of the JA number and if there is a JC numbers? I've never seen one that large. There is someone that has trying to compile info regarding Japanese machines with JA and JC numbers at
http://www.doubleveil.net/zssmp/resources.htm (about 2/3rds down).
Janey - Neat people never make the exciting discoveries I do.
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