Hum aint fun

With TT platter spinning, tonearm in its cradle, there is an audible hum through the speakers. When arm is moved over the record on the platter the hum just about goes away. Hum is non existent when stylus is on the record. What gives??
Do you have built-in or separate phonostage?
What tonearm?
If you have separate ground wire on your tonearm, try to connect it to a different chassis other than phonostage...
separate phono stage. Thorens td-124 with ortofon rmg-212 arm.
If you don't have a ground wire from the metal (if metal) turntable chassis, try one from it to the preamp phono ground.
Hifivn- thanks but i already tried this and it has not changed
If there are no wires under it, that's odd. No AC shielding through a wood arm mount though, if that is the case. Could the hum possibly be the mechanical vibration from the motor coming through the cartridge? Hard feet, or something else that made the suspension (springs/rubber?) stiff, will sometimes intensify a mechanical hum.