It is difficult to get the musty smell out of the case but not impossible, but for the machine take off the bottom plate, check out the felt drip pad, that is probably the cause of the machine smell if it has absorbed the musty smell. Google "glenn Miller 221 parts" & you'll find a source for parts, he sells the felt pads, rubber feet (a good chance they are worn down), bobbin winder tires, etc,
very reasonable.