Ruiz, some of us on the board have tried the Singer 66 bobbins from Joann's and Walmart on our vintage Singer 99's and they don't work. There are better places to get ones that do work like at sew-classic and other places on the net. Congrats on the machine. We want to see pictures of it. Welcome to the board.
Janis
I just looked up your serial number EL047675 here :
http://www.sewshop.com/docs/SINGER_EL_nos.pdf
And your machine's number was aloted Jan. 24,1956