Grounding Hum

I recently got a new TT for Christmas. It's an MMF 2.2 LE. I think there's a grounding problem or something because there is a slight buzzing noise present. I looked through past threads on the topic here, but nothing seems to fit this situation. I've checked, and rechecked the connection between the TT, and the preamp. I've even used a Fluke voltmeter to check for continuity between the two. I've checked the headshell leads to the cartridge. All is well. Maybe it's the ground wire connection to the turntable itself? I've run out of options. Any ideas?
You might try this, it has worked for me once when I had a similar problem. Affix an alligator clip to a wire. Connect the wire to your preamp and clamp the clip to the base of your tonearm, from underneath if possible. Its worth a try, good luck!
The cartridge may be picking up hum from a transformer in some piece of gear nearby....have you tried moving the MMF?
I just tried the separate piece of wire trick. That didn't work. Now, I'll try moving the 'table and see what happens.
Here's some additional information, which may help:

If I flip the switch on my preamp (NAD1155) from MC to MM, the hum reduced, but doesn't go away. However, it seems that I, then, act as ground, because there is a more pronounced hum whenever I touch the preamp. The hum comes from both channels. A bypass wire from the turntable to the preamp had no effect. Moving the turntable (to the extent that I could) had 0 effect. The amp (B&K ST-140) is connected to a Stax SR34 headphone preamp. Then Monster Cables from the Stax unit to Vandersteen speakers.

Thanks to all those who contribute to my problem resolution.

Try flipping the AC plug-ins around in their sockets one at a time. If your on split phase with ground return this could help. Let me know if this helps and I will explain why it does.
Weird, but worth a shot is to try grounding your preamp to a piece of digital equipment, like your CD player or DAC. If that doesn't work, try the same, but with the ground from the turntable to the digital piece.
I had a hum on my TT as well. Had to crank the volume up a bit, but it was there. Turns out it was my TT lite. I unplugged it from the Richard Grey 1200s (the lite) right under the phone stage to the shunyata hydra on the floor and hum is down 90%. Only apparent when I crank volumn up to 90 (out of 100). Will play a bit more but I may just live with it until I upgrade...something.
The situation gets weirder, and weirder....

As any good technician will do, I disconnected everything from preamp, still a buzz. I even unplugged the TT! After that resounding flop of an experiment, I swapped out the amp. Still a buzz. So I've eliminated the CD player, the TT, and the amp. All that's left is the preamp, the Monster Cables, and the VPI 16.5 (which is only drawing power when I'm cleaning an LP). The Stax headphone preamp is going to get taken out Sunday morning. Then the plugs get reversed. The other thing I thought of is that I have PC plugged in to different outlet, but they could be on the same circuit. I'm scratching my head over this one... Grounding is certainly an art, not a science,

Well, there's more than one way to skin a cat, and this cat will get skinned!
I have been dealing with noise/a hum in the path of my turntable and phono preamp. It's a royal pain. The only other suggestion that I have heard that has not yet come up here is to find a cheater plug (on that reduces the three prongs to two) and try that on the amp and the turntable.

It appears that my noise is a result of outside interference (radio, tv, ???). I'm trying some different cables as well to see if I have any more luck reducing the noise.
I've tried every suggestion, but still no success. I've even tried "shielding" the preamp, the amp, and the TT with tinfoil. No luck. Any other suggestions? I'm scratching my head so much it may start to bleed.
I had a hum coming thru my preamp from a little 12V transformer used to power something unrelated that was too close to the pre.....look around the unit for anything that might cause the problem. Also turn off any dimmer, automatic light sensor and flourescent fixtures anywhere in the house. (auto light sensors and dimmers can create havoc).
Is the IC that runs from your preamp to amp shielded? I recently had this same problem and discovered that it was said IC and not the TT ground. Switching to a different IC did the trick for me.
It's Monster Cable interconnect cable, if that helps. Besides taking the cable apart, is there a way to tell if it's shielded?
I finally (3+ days) figured out. I pass along this update in the hopes that it helps someone else out. The source of the hum wasn't grounding at all. It was airborne RF given off by a Kodak camera dock in a distant room. All I can figure is that the electrical circuit for that device went through a wall behind my stereo system.

A big thank you to all those that responded.
Never mind what I said in the previous post. The buzz returned. After venting my frustration, I went to turn the volume up on the preamp, so I could the noise while I went around the house searching for the source. When I went back to the preamp, I inadvertently touched the faceplate, thereby grounding it, and the hum stopped. My conclusion is that the preamp itself is having a grounding problem, that only be heard when the phono input is selected. So the issue becomes one of grounding the preamp. Any suggestions? I don't want to have to act as the ground myself...
I didn't read back in this thread...but have you tried the phono input with the phono unplugged...and plugged in? Is there a difference? You might have a loose ground wire in the cartridge assembly/connector. Can you try with the cartridge removed?