Thanx for the info people. Learned a lot now. This question popped into my head the other day when I was going over my plane. It has stood for 2 months now, since our weather was either too hot to fly or the wind was crappy. Well tomorrow looks better so we are heading out very early. Anyway, so I was checking everything again hinges, nuts, servos, starting up the engine etc etc. When I took the glow plug out and hooked it up to the driver to see how the glow is on the plug, I noticed that the top part (first or so twist in the coil) wasn't glowing. I suspect I need to replace the plug or soon?