Have any of you experienced a fan that appears to fit too far on the shaft. I'm replacing my four blade with an aluminum two blade. When I tighten down the castle nut, the prongs go past the hole where the cotter pin goes. In other words, the cotter pin won't prevent the castle nut from loosening because it isn't seated between the nut's prongs. Could the shaft possibly have the hole drilled in the wrong place, or is there something else wrong? The four blade fan did fit any better, my dad just put two nuts on it when he had the car.