Rega Planar 3

Have a Rega RP3 and have the same problem. I have just learned to live with it. I have a Rega Exact cartridge. Not long ago there was a post on this problem and as far as I know was never resolved. My hum is not loud and I really don't notice it unless I move the tonearm to the center and turn the volume up. I don't notice it when playing a record but still I know it must be there. My solution saving for a  JA Michell TecnoDec hoping I can use the RB 303 tonearm. If you find out what's causing this please post i would love to know what Rega says. 

Will do. Oddly enough they have a P6 set up and a P1 that we turned on and moved the tonearm around and no hum so that's kind of bewildering. I will post when I find out.

So it's interesting to work backward on this.

Grounding wire issue? If so, then the hum should be there no matter where on the disc the tonearm is.

The grooves towards the spindle tend to be less bass-heavy and more out of alignment then the two null points before them (that's why, for example, Peter Gabriel's "In Your Eyes" was placed at the start of the B side of the LP; because of its heavy bass line), so is your cartridge picking up noise? But...

The hum's there no matter the cartridge, so it sounds almost like an internal issue - the tonearm wires; the AC motor.

Let us know what Rega says.