I need some help with my old sewing machine. When my newer(35 year old sewing machine:-) finally bit the dust I dug out this old baby.

It does the trick for what little sewing I do now. Problem is when I was filling a new bobin with thread the rubber ring you see on the white piece of paper fell from somewhere:-) Now the bobin does not touch the inner wheel enough for the bobin to fill.

Can anyone tell me where this rubber ring goes and how to fix this problem?