Here is a link to Nova Montgomery's site. She offers great monthly tips to care for your maintenance, etc. This month she addresses the odor in the case. Interesting because it isn't the "case" but is a result of the wood pad in the machine's drip pan. She also tells how to remedy the problem....plus oh so much more. She also has Featherweights for sale that she has personally serviced and used.
http://www.novamontgomery.com/quilt-guild-programs.htm