Lily, I referred your problem to Mrs Didge who is a whiz at keeping old sewing machines running (she's still using a Singer she bought in 1958) and she said your solution appears to be simple. Pray.
Ok so now I know that I totally broke the sewing machine. It won't sew, the needle won't move, the knob won't turn. I've cleaned out all the pieces, there is no sight of a jam or anything. Help!? This sewing machine is special to my mom.