Walt I forgot to mention:
You should loosely spiral wrap the additional ground wire by wrapping it around the tonearm cable pair for the full length. Fairly widely spaced coils perhaps 1.5" to 2" apart. Then attach to the ground post. This should help to prevent ground loop hum pickup.
You should loosely spiral wrap the additional ground wire by wrapping it around the tonearm cable pair for the full length. Fairly widely spaced coils perhaps 1.5" to 2" apart. Then attach to the ground post. This should help to prevent ground loop hum pickup.