The stink comes from the glue made from horse hooves that was used in the earlier cases. Nothing will get it out for good as its embedded in the case. There is a nice case on the Featherweight shops online. And think Quilt in a Day had some.
https://singer-featherweight.com/col...nt=38426897731
https://featherweightdoctor.com/prod...shoulder-strap