Our well rig did that, there were burrs inside the distributor gear. The retained also fell off of the shaft and it pulled out of the oil pump, or something like that. Check those things out. The burrs were cleaned up with a allen wrench.Drill bit to the distributor, still couldn't get it to sit down all the way. It weren't seated when i got the truck, but they all should be the same so not sure what i'm doing wrong