I didn't watch it all, but I know some have recommended this person's videos, this video about cleaning the 99 thread tensioner at
https://www.youtube.com/watch?v=rioRhSbog6U It does have a numbered dial, which yours may not have. Maybe
http://mysewingmachineobsession.blog...6-or_2926.html would help.
Janey - Neat people never make the exciting discoveries I do.
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