I have another theory: the pulley at the bottom right passenger side at the bottom of the engine (water pump?) where I have mentioned before there is NO room for error tracking. It would not take much, either a slight misalignment upon installation at the factory, or, even a very small piece of gravel or cinder kicking up from the road, get wedged in there, and misaligning the belt. That pulley seems VERY exposed to all the elements.