I've had this happen before more than once. When you have multiple machines, you're bound to have one you use primarily, so the other ones sit waiting for their turn. When machines sit for awhile, they can freeze up. But isn't it a great feeling to know that if you give them a dose of oil, they'll spring back to life? I have both computerized and vintage mechanical machines. I love them all, but my vintage machines will probably still be sewing long after the computerized ones lose their minds.