I had to re-tap and clean a stubborn bolt hole... more specifically one of the bolt holes that supports the alternator. The old bolt loosened up on me, allowed the alternator to vibrate more and more till the pulley bearing seized up and screamed and smoked, leaving me on the side of the street in West Hartford in the pouring rain with inadequate tools. Well that was fun. I limped her home on battery power that day with the fresh air vents CLOSED (you know where the "fresh" air comes from? right behind the engine compartment!)