I finally called them on Thursday. After a not too long wait time I got a nice woman on the phone, who listened to what was going on, walked me through some VERY easy steps of taking out the roller and drive belt, and helped me diagnose the problem. Turns out we needed a new belt, but since they redesigned the belt-brush combo since we bought the thing, Dyson is sending us a new belt and brush for free! How totally awesome is that? Should ship out soon and be to us soon.
Also, I love that it was that easy to take apart the vacuum (didn't even need a screwdriver) and to find the serial number (it's under the canister). So well designed!
I hope this vacuum lasts us many more years, but when it finally breaks down I have a feeling we'll be buying another Dyson.