Another point to consider or try....is to remove the wire going to the glow plug.....and put a freshly charged glow plug igniter directly onto the glow plug.....using that as your heat source to start the engine with. I know it sounds a little off....but I finally took my blue wire off and now only use the glow igniter to heat up the plug. That way I always know I have a good heat source getting to the glow plug.