Clubsport, that which you describe as a crack in the dizzy cap, could well be a... track... which can be created as the result of a high resistance elsewhere when condensation inside the cap can provide a less resistive alternate path, once the path is initially established, it is possible that carbon builds up creating the track and can etch it`s way into the surface of the plastic to look like a crack... Electricity like water, will ever take the least line of resistance, or if you prefer the easiest route.. Of course you may well already know this..
