Every now and then I get a machine that almost smells worse than the storage case it came in. Spit your gum out so you don't swallow it and don't start yelling "No Way!!!" and we'll get underway.
There are machines that smell so bad that there is no living with them. Between cigarette smoking (by former owners (remember, when these machines were made it was almost mandatory that you smoke to be an American) and the common mildew smell, although the case might just be beyond hope the machine can be cleaned up.
First, loosen the motor attachment screw two turns. Remove the motor drive belt and then wrap the motor with plastic food wrap snugly. Tighten the wrapped motor's mounting screw without the belt being reinstalled. Remove the drip pan from the bottom of the machine and replace the drip pad normally glued to the inside surface of the drip pan if your aim is to eliminate "the smell".
This will remove one source, but not all sources of the smell. Remove the spool pin cover, and the face plate. Put a piece of cardboard on and fitting the bottom of your kitchen sink with a hole for water to drain through it. This will protect your sink because we are going to wash the interior of your machine using hot water, hand dish-washing soap, bottle brushes and a toothbrush, your spouse's, not yours. A half inch wide natural-bristle hobby paint brush will clean the gears well as long as we are in there.
I already told you to spit out your gum before you swallowed it. Preheat your oven to the lowest heat setting, be that "WARM' or 150.
Now, listen, wash out the inside of the machine and avoid running water over the exterior of the machine. Do a real job of scrubbing the interior, don't poke at it and then write to say it didn't do much. Get a bottle brush all the way down the inside of the arm of the machine as best you can and then a little and scrub. A little water will not destroy your machine but do not let the water and soap pour over the outside surface of the machine.
If you honestly did due diligence go rinse the machine one last time. Shake the water out of the machine or blow it out, blot the exterior dry and then put the machine in your oven ( which you have preset at its lowest "warm" setting) for five minutes if you don't have a hot sunny day working for you.
I know this sort of thing is way out beyond many of your experiences in life for some of you, but believe me, it works and it will not harm your machine.
Do not set the machine down soaking wet and go take in a movie. Dry it out!
Oil the machine and grease the gears.
Take the food-wrap off of the motor and reinstall the belt. Remember the motor belt must be as loose as possible without the motor pulley slipping.
Your machine will not rust away, it will not destroy the machine or any other superlative you can come up with. This is not something to do each Saturday night but if you are like the woman I had in class who could not sew on her machine because it smelled so bad, this can save your day and your machine's.
I have done this many times now and it really does work and it will not hurt your machine. I had one person take my advice and said she was not impressed but she said she was afraid to use the brushes in the machine and dish washing soap seemed so harsh. Please, if you are willing to try it, do the whole job.
Source: Dave's Blog