There is also a "groups.io" site for vintagesingermachines that should be able to help. There may even be a special featherweight group - I don't know as I've no featherweight. Very knowledgeable people and I'm almost positive I've heard this issue addressed already, so you may find an answer without posting. You do have to sign up to access everything though. I signed up for vintage singers, vintage machines (in general), vintage Kenmore and treadleon (specifically for treadles). Discussions are limited to machines only. No chit-chat, no politics, no sewing - just machines.
I don't do facebook either.