I am teaching my sis how to sew on one of my Grampa's old machines. He fixed them for years. She has the 99k and I have his 1935 15-91. They both work great. Get some good quality sewing machine oil, and download a manual for the 99k, then oil the living daylights out of her. The following is a great website if you need more info and parts for your new(old) machine and Happy Sewing!
http://shop.sew-classic.com/