I have the same sewing machine and stool! I was using it today to reupholster leather cushions. I call it my 'tank'. You just can't find sewing machines made like these anymore. I was sewing thick leather, in 2 layers it came to a full 1/4" thickness. It didn't even hiccup. What a great sewing machine! I have the Centennial 15-91.
Christine-
http://quiltdasher.blogspot.com/