I may have just read the instructions wrong, but I put the grease under the diodes and it completely insulated the secondary from the plate. I ended up cleaning the divots with alcohol and a sharp **** driver till shiny, then mounted the diodes dry and put some of the grease on the side of the diodes to help transfer heat to the plate. Also, make sure the washers are installed exactly as shown and I believe the instructions say something like tighten till firm resistance, but make sure you tighten till the clamping plate is snug to the washer and fuse plate or you also won't have continuity through the diodes. Other than these little issues, it works great and is an awesome value to keep these old heavy duty chargers going!