Hi, First post here at Hobby-machinist. Thanks for indulging. I joined because I recently bought a Sherline 4000 lathe from a local private seller. It is a DRO model with the "B" package and numerous additional accessories, including 21 QCTP holders. It's completely unused; even has the protective coating on some parts and original unopened packaging on others. In any case, my real question is about the motor on this mini-lathe. I turn it on and the motor works fine, including speed control. However, there is a 60Hz hum coming from the motor at all speeds and this translates to a 60Hz buzz through the motor mounts. I know the motor is DC and my expectation is that the motor would be completely silent when running. Is this normal behaviour with other people's Sherlines or do I have to contact Sherline for service? - Robert.