First of all, I'd like to say I did my homework on this one. I checked the Park Tool site, Sheldon Brown, and some others. Basically what's happening is that one side of the brakes is hitting the rim before the other. Even if I have the pads perfectly centered, when I pull the side where you release them is moving before the side where the anchor bolt is. I've tried adjusting the transverse and cable that comes from the brake lever. I've tried centering them with the allen key on one of the cantilevers. I've run out of ideas.
One thing I do see is that after I squeeze the levers, the carrier seems to move off to one side. It doesn't seem perfectly centered. How can I change that?