What would cause...

Take Liz's advice

Wait. Think of upgrade too. I had older model, but I believe the new one also have motor EMI isolation issue. Overall, I was not impressed of its performance.

Everyone seems ready to jump all over the seller without giving things a good look. I would think the first thing to check would be the RCA jack at the pre-amp. Wiggle the plug and see if that makes a difference and also try coating the plug with De-Oxit. Problem may also be a loose pin in the cartridge. Try it in another tonearm. Trouble may well be in the tonearm wiring but I'd check the simple and obvious first.

Sounds like an intermittent electrical wire/connection issue inside the table. That would be a defect!

If new, I'd take it back to the dealer to assess and address the problem, including making sure cartridge setup including wire connections is good as well. There should be no intermittent noise issues that result from jiggling wires (within reason).

In lieu of physically taking the table back to the dealer to address, I would lean towards contacting the seller to return, and see what they can offer up in terms of customer service to your liking from there. COuld range from tech support coaching you through, to a flat out return or exchange, whatever is needed to make a happy customer.

All previous posters a/o Mapman 10/1/13 are correct. The arm has a ground fault in the left channel. Could be in the arm itself, could be the RCA cable, could be the headshell, could be the cartridge leads, could be all of those. Not worth fooling around with yourself.