You know I had a similar experience with my LT 1000 back a few years ago. Only my circumstance was cutting grass growing through driveway gravel at the edge of my drive near a culvert. Nothing broke or gave me any indication that my mandrel was in need of replacement until I went to replace the blades. I hardly ever sharpen my blades, usually just buy a new set or two every year. This time I couldn't get the old blade loose because the bottom of the mandrel had somehow become mushroomed and locked the blade in place. I finally sanded the mushroomed metal off and got the old blade off, but then couldn't get the new blade on all the way. Weird, because the bolt and washers holding the blade on were okay. Somehow just the "star" part of the mandrel got deformed. Since the bearing was a little rough, I just decided to replace the whole mandrel. It wasn't too bad of a job using my air impact tools, but I'm now extra careful about what I mow over-it wasn't that much fun replacing the mandrel! Good luck with fixing your mower.
