Help VPI turntable hummmmmmm

I have just installed a new Naim system with a VPI Scoutmaster and the TT hum is not quite deafening..............but getting there. Can someone please help!! Do I need to earth the TT to the phono stage? If I do I have tried this but no success. What am I doing wrong. There is also an audible 'thump' when switching the TT motor on or off.