Originally Posted by Gerald C Koch
...it is not the neon bulb that is failing but the main capacitor that powers the flash.
Yeah... What he said ^^^.
Capacitor failure is extremely common, almost guaranteed if the flash is more than ten years old.
It's an easy fix (replace the capacitor), but may not be worth the cost depending on the size and quality of the unit.
“Wise men talk because they have something to say; fools, because they have to say something.” - Plato