slight 'buzz' fr rega p1

my rega p1 w a stock ortofon 0m5 cartridge has a very slight electronic buzz. once the lp is playing, in no way can it be heard, even at very low volumes. in fact, you have to get really close to the speakers to hear it w no music playing. however, when i pinch the tone arm beteen my fingers, the buzz is gone. i am playing through the phono section of a jolida musical envoy tube preamp. the buzz is not at all present when the preamp is set to other inputs, such as cd or tuner. could it be a grounding issue? i dont think the rega a grounding screw on the chasis and i know that my preamp doesnt. not really a big deal, but i am hoping someone has some ideas. thanks in advance for the help.

 

I don't know if the P1 has the exact same setup as the RP1, but I experienced a similar problem with my RP1. After many experiments, I finally removed the end stub from the tone arm and discovered that the copper strip which must stay in contact with the tonearm to ground it had come loose and was bouncing around inside the tonearm. Reseating the copper strip so that it was held in firm contact against the inner surface of the tonearm dramatically improved the grounding and more or less eliminated the hum I was experiencing. Eventually, I ended up rewiring the arm for a dedicated ground wire, but that is another issue...