Todd -
My money is on dry centerpost bearings. I have heard the very slight beginnings of this in a couple machines in my active collection, then noticed it loudly in not-yet-in-service machines which have been sitting for some time. Ironically, my coppertone 1964 Kenmore 70 series, is a great example. It has been unused for over 20'years. Its bearings are so dry that the howl caused by metal on metal is unmistakeable. Over time, centerpost turbine oil leaks past the seals...there is only a couple teaspoons of it anyway.
While I can see how worn clutch pads could cause some noise, I have never heard much from them. The worst I have come across had worn far enough to wear half the heads off the rivets that hold on the clutch pads. There wasn't much noise that I recall but it would occur only in spin acceleration.
The worn spin pulley bearing makes a very unpleasant racket, but this stops the moment the machine goes into spin as the pulley stops rotating on the spin tube and the whole pulley/spin tube assembly begins to rotate as one.
For those reasons I'd think about lubricating the bearings --- it will help in the long term serviceability of the centerpost anyway. We'll help you thru this process if you need coaching, etc.
GOOD LUCK!
Gordon
