We have had about 200 CUCVs swollen glowplugs are a common problem Its not just carbon they go so big they will not come out the hole. Heres our removal process: first we get the engine warm, unscrew the plug, clap a vicegrip on it, pry with a large screw driver between the vicegrip and head, while rotating glowplug. When that does not work remove the vicegrip start the engine with the glowplug loose, if your lucky, The compression will beat the glowpulg up and it will fly out. When that does,nt work remove the injector and snap off the glowplug, usually the broken piece will be too long to slide into the prechambers use a small punch through the glowplug hole and tap the broken piece into the prechamber, typically this piece is about an inch long it is too large to fall into the cylendar, some glowplugs are magnetic, so try to pull it out of the injector hole with a magnet when that does not work, fish it out with a medical needle nose "hemostat". I have had several "mechanics" say just leave it in there and it will blow out the exhaust, i had one CUCV towed in with a supposed rod knock, what had happened was the glowplug tip had made it into the cylendar and was getting hammered between the piston and the head, I know one man that replaced an engine and then found out that this was the problem.
Just two weeks ago another guy called me confident his engine had just thrown a rod, I told him to pull the glow plugs, sure enough one was shorter than the others. He pulled the head carved the plug out of the piston smoothed in the dents and its happily thumping down the road. As far as not having a vehicle down or the time involved the longest it has ever taken me to remove a glow plug by snapping it off and fishing it out of the injector hole has been two hours, as to getting dirt in the injector hole, try to be clean, but the simple fact that your beating on a junk glowplug means you will knock all kinds of debre into the prechamber, thats why god invented the air blow gun