Ok, well I ran into this problem a few days ago. As i was changing my glow plugs, as i was taking an old one out, the socket was stuck on top of the glowplug and under the lifter. After some thinking and not really many ideas, I figured bending it would snap it. So to test how much i could bend the glowplug, I put one on a vise about the same angles i was dealing with and literally bent it at a 90 degree angle. So if you run into this, bend the glowplug in the socket enough to pull it out.