Learn how to clean the insides of a vintage sewing machine so that all of the mechanical parts work as smoothly as they did when the machine was first made. It's a valuable skill to have if you plan on buying more than one vintage machine.
If you want a fully mechanical, gear driven, totally metal vintage sewing machine that will last forever. Singer Slant-O-Matic made in I learned to sew on one of these and own one myself. Mother is still using hers, bought new in