Ignitions tend to break up when the voltage gets low rather than just fail.

The moral of the story is, if it ain't broke don't fix it This could be anything from improper assembly to possibly when you were cleaning out the carb a piece of dirt got into the H circuit. I would double check assembly and pulling out your needles then clean them from the back side to make sure there is no dirt inside them. A paper clip will sometimes go a long way.