EME 55 with about 5 tanks thru it installed in a 95" Howard Ike. Flight # 6 and it wouldn't start. Cranked it for about 15 minutes before giving up.

When I got it back to my shop I pulled the cowl, then the plug and attached it to the cap. When I rotated the crakshaft past the magnet, I got two sparks. One weak one from the tip of the electrode and a strong one from the hexagon base straight into the cap. I believe this is called leakage.

New plug tested in the cap produced a good spark at the electrode and then installed in the engine and it started right up as good as ever.

Has anyone ever experienced this before?