bkay

Clean the machine with Go-jo or some other non pumice water-less hand cleaner. Wipe it on and wipe it off with old t-shirts. Use a toothbrush to get the hand cleaner into the crevices. Once you get the ugly yellow stain off, most of the odor will be gone.

I would not use water on a sewing machine.

See if you can get someone who is not so sensitive to the smell to handle this chore.

Or, if you just want to get rid of the problem, do what was already suggested. Put it out on the table at a meeting with a $??.00 price tag on it (if you want to make money for the guild) or a "free" sign on it. Just make sure the buyer knows it stinks.

bkay