Help Problem with Cary 303/300

My 303/300 is only 6 months old, and the left channel output (analog RCA) is dropping. Not completely, mind you - it's about 60 dB below the right channel.

My preamp only takes RCA plugs, so I can't simply bypass this problem by using the other output jacks.

Has anyone else run into this problem, and if so, did it require service at the factory, or was there a simple solution you could do yourself?
The player has both tubed and ss outputs, is the problem occurring in both? It could be a bad tube if you're using just the tubed output, to isolate it try swapping the tubes between the channels and see if the problem moves with tht tube. If it's anything but a tube just wait until Monday and call Cary.
Problem solved. It isn't the Cary after all. For some reason, when I push the Eichmann bullet plug all the way in on the left channel of the DNA-125 the channel drops. When I pull the plug out a couple millimeters everything is fine.

Thanks for your idea, Jon! Next time around it could be a tube, and I'll know to check it.