Originally Posted by
bonnyh
My husband, our local sew and vac mechanic, suggests it's the upper crank shaft and its components. They need to be cleaned and lubricated. BTW, he uses gun oil, not sewing machine oil. It's also a rust inhibitor as well as lubricant
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Bonny,
That is / was my conclusion too. Something to do with the upper shaft. No matter how much I cleaned or oiled it simply would not go away until my wife had sewed with it for good while.
It's been my experience from use as well as reading the labels that a good gun oil and sewing machine oil are pretty much the same thing.
Joe