UPDATE: I'm still getting the buzz feedback but in a different channel now. Nothing happened when I jostled the connections on the TT's tonearm: the buzz was still there and no music came out of the right speaker. I unplugged my phono preamp all together and connected the TT directly to integrated amp's built-in phono pre-amp. Doing this, the problem shifted shifted to the left speaker: now I'm just getting sound out of the right speaker and no sound and a buzz out of the left. Any new thoughts?
Turn the stereo off, disconnect the wires from the cartridge VERY CAREFULLY. Turn the stereo on, but set the volume to a low level. Touch the red wire's terminal. If you hear hum, it's OK. Then, touch the white wire's terminal- if you hear hum, it's OK.
At this point, unplug the cables connecting the turntable to the stereo or phono preamp and use your meter to check continuity on each. You should have no continuity between wires, but you might as well check that, too.
If any wire is open, it needs to be repaired. If you have any short circuits, likewise.
Why are you using a separate phono preamp? Is the one in the stereo not good enough?