You will need the grounding carbon button to make contact with the back of the shaft, or replace the grease in the bearings with a graphite loaded grease, which in this small bearing will be both hard an will reduce bearing life considerably. the thing with a spinning bearing is that the inner and outer race tend to be separated by a thin film of oil from the grease, effectively insulating it, and if the applied voltage is high enough then the breakdown of the grease causes a small arc which eventually erodes the bearing raceway and the balls. When you open one it is full of black deposits and the raceways and balls are badly pitted.