Originally Posted by George16

Fill the hole half way with solder.

Best way to do it is by using a piece of wood. Drill 6.5mm holes on the the piece of wood, place the 6.5mm plugs into the holes. This will allow you to keep the gun on the plugs to allow the sloder to fully melt and flow into the plugs. Once the solder is in the hole, insert the wire and cool it down.