Here is an old mechanics trick to avoid cross threading. First of cut about 5in of rubber tube that will fit firmly on the top of the plug. Gap the plug with a good wire plug feeler guage. Hold the tube by the other end with your finger tips and insert the plug then tighten it finger tight with the tube. Pull off the tube, torque the plug down to specs and re attach the plug wire. Be sure it is seated well on the plug.