Ground Hum

I need some suggestions eliminating ground hum from my VPI Scoutmaster.

Cart is a Shure V15Vmxr (or whatever it's called)
Tone arm is JMW9 with stock wiring
Preamp is Dynavector P75.

I have tried a few different cables ranging from monster cable to cheap stock audio cables you find with most electronics. Makes no difference. If I touch the tone arm wtih my finger, the hum gets louder. If I touch the gold connectors on the back of the turntable the hum goes away. Touching any other parts of the tonearm output block or the preamp causes hum to get louder. Any suggestions?

Did you connect the ground wire? If not, it will hum.
Sorry failed to mention, yes the ground wire is connected. Disconnecting it made it slightly louder.

Run a ground wire from the dynavector to the tonearm headshell. Does it go away?

Run a ground wire from the headshell to your main preamp. Does it go away?

If it does go away that will tell you at what point the problem is.

Make sure your rca plugs are clean and make good contacts... Most likely you have a break in your ground wire.

Other possible cause could be the pivot point needle bearing is dirty and breaking the ground, or the contacts to your cart are damaged or dirty.
Try turning the power plug 180 degrees...use a cheater if you need to. Sometimes the hum comes from the 3rd pin - eliminate that for further experimentation.
Try this. There should be a grounding point on the arm itself. See if there's a screw hole on the support for the arm post. Feel with your finger along the right edge. If there is, install a small screw and attach a ground wire which you will then connect to the arm's main grounding point. It's there on my JMW 10.5, but unmentioned in the owner's manual. If it's not there on your JM-9, forget I said anything :-)

Good luck, Dave
There's already a ground wire running from under the bottom of the tone arm assembly under the turntable to the grounding lug. I have another wire running from that grounding lug to the ground on the P75 preamp.

Okay, you might try removing the ground wires one by one and see if the hum inceases, decreases, or goes away. And reroute the under-turntable ground to the JMW9's main grounding point (between the output jacks). And did you check to see if the screw hole I mentioned is there or not? Dave
Since the ground is connected, make sure the headshell wires are fully connected and going to the correct pins.
Is the cartridge new? Has the hum alway's been there with this cartridge? Have you used the turntable/arm with a different cart. or the cart. with a different turntable?
Can't help wondering if the cart. has an open loop(defective). If so, no amount of grounding will make the hum go away. See if you can try a different cart. or this cart. in a different setup. If it was purchased thru a dealer have them check the cartridge out.
Let us know what happens.
Try shielded interconnects that solved the problem for my Scout.
I've been wanting to upgrade the cart anyway, so I will give that a go. I have tried different cables, Monster Cable to inexpensive standard audio cables, no effect. I'm leaning towards the cartridge. I've had the cart on a previous table before I got the Scoutmaster but I did buy it new just as the Shure V15 series ceased production.

Did you have the hum like you do now when you used the cart. in a different system? If not, it's doubtful it's the cartridge.
I know you've tried lot's of different phono cables, but where any of them shielded? If your not using a shielded cable it can cause a lot of hum as your describing.
Thanks for everyone's input. When I have more time I will try every option given here until I narrow it down.

I have found a way to eliminate the hum. Though this may not be ideal, the solution was simple. I ran a strand of bare wire from the ground lug to one of the rca output jacks of the tonearm connection block on the rear of the turntable. Hum is now gone.

Been there done that. Your descripion sounds exactly like mine did. At the base of the turntable tonearm is a phillips screw.Go to Lowes or Home Depot and get a grounding rod and connecter.At home drive the rod in the ground outside as deep as possible near your system or room. Connect a solid wire to the base of your tonearm to the rod outside and anything else you want grounded. Still do the typical grounding to your preamp. This solved my problems with hum.