Diagnosis: Cartridgecide

I have been in the process of setting up my table with a brand new Dv-20xH. For the first three minutes or so on the outergrooves the channel balance, and seemingly everything else, is fine. Past that, the right channel becomes attenuated like the singer is leaning against the left speaker. A further oddity is that when the arm is resting in its holster, the right channel buzzes/hums.

I have played with what there is of an anti-skate (rega), VTA and azimuth(looks good, but there's little i can do wiht this parameter) and the problem is persistant. Overhang is good as well. I also switched L/R interconnects to rule out my preamp. I'm stumped.

Normally I would just take to the dealer, but England isn't real handy when you live in Dallas. And god knows if it goes to Enlgand, it's going to go to Japan. I just want to make sure before I send it on a trip that I only wish I could go on. Is there something I may be doing wrong? Is there some definative way to tell if she's actually gone? I really do not remember doing anything bad to my cartridge.
This sucks. Thank you.