Rega P5 Hum

I don't listen to vinyl much these days, after having rediscovered it a few years ago. I think that the improvements in Digital over the last 5 years (particularly in DACs) have greatly closed any gap between analog and digital.
One of the reasons that I don't much listen to my vinyl rig is that it has become a pain in the ass. My Rega P5 table has developed a massive hum that seems resistant to every other change I make in the system. the p5 doesn't (I should say didn't--it has been discontinued) come with a ground wire. Supposedly the ground is contained within the wires from the tonearm to the phono preamp. If it did have a seperate ground wire, I might be able to get rid of this noise.
Any suggestions?
Don't know what to tell you-but there must be something wrong with your P5-I've owned several Rega tables over the years, none of them came with a ground wire, and none of them had any hum whatsoever. You don't by any chance have a Grado cartridge? I have heard that some Grados hum on Rega turntables.
Is the hum there with the P5 AC power to the motor disconnected?
Checking that would help with diagnostics.
If it goes away with P5 A/C disconnect, then it is the motor or cap.
If not.???
I also own a P5 but have never had any issue with hum.

You also might try a ground wire from the arm base to your preamp? Just lift a screw on the base and stick the wire under it and screw down. Even a very thin wire will suffice. IF that works, IMO a wire in the arm is worn/frayed. (most likely right where it comes out of the armbase under the TT board. You could flip it over and look at it easy)