The HA-1 aka 15 clone manual can be found at
http://ismacs.net/singer_sewing_mach...ion-manual.pdf
The thread regarding tension assemblies, that Miriam did, can be found at
Taming the 15 clone tension... well maybe.....
There are a variety of tension assemblies on 15 clones. I can't find it now, but it seems like there was a 15 clone that had a tension assembly like is shown on page 17 of an adjusters manual for the 15-91 (and others) that can be found at
http://parts.singerco.com/IPinstManuals/15-91.pdf It seems like I have also seen a tension assembly similar to the one on my 115 as shown on page 13 of
http://ismacs.net/singer_sewing_mach...ine-manual.pdf
Not affiliated with non-QB links
I looked in my spreadsheet and I don't have any JA or JC numbers listed for any of my clones. It doesn't mean they don't have any, I just didn't put them on the spreadsheet if they did.
Hope this helps.
Janey - Neat people never make the exciting discoveries I do.