Here is a picture of a Featherweight bobbin case.
Concerning the smell -- the first thing I would do is to remove the bottom of the machine and replace the felt drip pad. It can be really rank. You can cut a new one from felt type material and slip it in place. The other source of bad smell can be the machine case itself. People have offered you deodorizing solutions for that problem.
Let us know tomorrow how it goes when you try it out.
Dayle