Even the vented ones arent that great either. Most of the ones that we have worked on and that failed got moisture inside the optical eye got covered over. The inside rusts and distorts things. And today we did one on a car, the bearings inside froze up and the rotor just exploded inside the distributor.

Usually when the water pump starts to go, it drips right on it since its right above it. It is costly. Its around $120 for a new water pump and $300+ I think for a new opti spark setup. Ive been told you can buy a whole setup from a direct gm aprts website for $250. You can get rebuilt ones at autozone. They do come with a lifetime warranty.