VPI 10/VPI MK IV/Grado Reference HELP

Can any of you help, getting low hum through the speakers when TT is turned on,
the arm is over the LP but not all the way down. Also the
volume is turned up to listeing level.
Three immediate things to check:
1. make sure TT ground is connected to good ground point;
2. make sure preamp ground is good;
3. make sure that interconnects are solidly seated.

If all this checks out OK, you may have a ground problem with the cartridge.
Agree. Make sure all the cartridge connectors are firmly seated, too.
Don't know why,but my table is quieter without the ground.
Is it a HO version? 4.5 mv? The Grado HO are known for this but usually at the end of the LP before it starts.I have a minor hum then but it has never been audible during music.Im not familiar with your table but if the motor is not under the platter than forget what I wrote above,its something else.If the motor is below the platter aluminum foil applied under the platter has been reported to eliminate the hum.All I can offer you,sorry...
Try reversing the TT mains plug in the socket. May not do anything, but worth a try