The treadmill is Sole F63, about four years old. Developed annoying monotonous noise seemingly coming from pulley-motor assembly. The noise is humming, but loud. Goes louder with the load (if walking on the belt). To me it sounds as coming from the motor. The belt is like new. No squeaking or grinding sound, just loud humming. I have a video with the sound but do not know if I can place it on this forum. Help!