I am an engineer. I have an X300 that breaks belts. I have researched every tech article on the subject. I have replaced the mechanical pieces with Deere parts, I am aware of an issue with a lifting bolt hitting the belt. I finally suspect an improper dealer setup! there are two adjustments to the U device that connects to the front axle. The "keeper" bolts were never tightened! I cannot locate a true description of how to adjust the length of this assembly that affects the belt tension. NOT the front deck lift adjustment! Also, what is the correct belt tension? I have the tools for all. This is a very common issue with 2 blade decks. As an engineer, I am sorry I bought this.