Perhaps the body of the pilot jacks are not insulated from their mounting holes. The insulating washers shoulder must not be thicker than the material the jacks are mounted in. Some washer sets come with one washer with a shoulder and one without for use in thin material while others come with both having shoulders. The sets having two with shoulders are used in thicker mounting material where the shoulders will not tough each other, but will keep the jack from rocking in the hole and
shorting to the mounting plate. However, in the event the jacks are mounted in non conductive material none of this matters.