I went and looked at your pics and I agree that is not the right bobbin case. One thing to definitely replace is the felt oil mat when you take the bottom off. Those that are in the machine when you get them are old and very smelly. You can order a new one on a lot of the featherweight sites. What Dave McCallum told us in one of his FW classes to do is copy the pattern for the pad and buy stiff felt at the craft store and cut out your own. Worked just fine! His book "The Featherweight and I" is a great book with great illustrations. He also has a disk out about caring for your FW. Their site is
www.Featherweight221.com and I've bought from him at quilt shows in the area and also ordered on line. He's very knowledgeable and I'm very lucky that he lives only about 40 mi from me and I had the opportunity to take his class.