I don't have a specific answer for you. I suppose you have searched for a the manuals you want with "319" without the "W".
Many of the vintage sewing machine groups have manuals in their files. There are groups on Facebook (I don't do facebook, so can't give you specifics.) Most of the old Yahoo groups have moved to groups.io. Try the "wefixit" group at groups.io. You have to join groups.io, then join the groups that interests you. There is/was a singerslantsewing group that might interest you. There was also a Singer sewing group, but I'm not sure they still exist.
Many group users have moved to Facebook, so many groups have kind of faded away.
bkay