Welcome to Quilting Board. As AlvaStitcher said -
do be careful with cleaning.
What a nice thought you have. A lot of us service our own machines. Frequently, these machines only need cleaned and oiled to get them working again. It appears to me that it is a Singer 15-86. It looks like it might be missing part of the tension assembly. Here is a site about a similar machine -
https://mermaidsden.com/blog/2017/09...ning-and-using However, some of the links do not work and is not very detailed. There are a couple of manuals that are close for this machine at
http://needlebar.org/main/sident/15.pdf and
https://www.sil.si.edu/DigitalCollec...0203/index.htm
One does need to be careful with who does the work. It seems like if they can work on modern machines that they should be able to work on vintage machines, but I have heard of some that do not.
Good luck in finding someone to do this for your sister. My brother and I restored the treadle that my sister learned to sew on. It gives me a warm fuzzy when sewing machines stay in the family and brought back to their original useful state of operation.
Janey - Neat people never make the exciting discoveries I do.
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