Hey guys, let me first say that I haven't dealt with the specific issue you guys are talking about personally, but I have a KTM 450 EXC DIRT bike. They have a problem with the wheel spacers getting the exact same "ring" worn into them and allowing dirt, mud or water into the bearings and eventually taking them out (The ring getting worn into wheel spacers is a common issue on every dirt bike I've owned). It comes from the spacers having a grease residue on them (totally normal from wheel removal/install) and attracting dirt/grit from riding that then burns the groove into the spacer. SOLUTION: Companies started producing wheel spacers that have a harder alloy/steel outer surface for the seal to ride on that won't get the groove worn into it. That being said, I should note that the original wheel spacers are only made of aluminum...