I've run into the same issue with my Gilbert 0.07 and 0.11 Engines: dwindling supply of strong glow heads. I drilled out the old glow element of both and tapped for std glow plugs. Have to be careful as the aluminum glow heads are soft, and the threads are easily stripped. You have to play around with short vs extra-short plugs and one vs two copper gaskets to get the right compression, or extension of the plug into the combustion chamber. But, it does work well, and allows you to use off-the-shelf plugs for what I consider to be pretty neat engines. I'll try to get around posting on YouTube a little movie of my 0.11 conversion . . . C R