I ran mine for over 5000 miles without incident. Was your pulley a used one machined down or a brand new one from MB? Only reason I ask is it spins the opposite direction when you run the belt under it vs over it. If it was previously used, I could see the bearing not liking it and giving it up because of this. If it was new, I got nothing.

Mike, what would it take to machine up a few with the outside ribs to help keep the belt tracking on the SC pulley correctly and the appropriate spacers and then press in a better bearing? I'd be on this is a second. Also, if you're up for making another oil pressure standoff, shoot me a PM or give me a call and let me know what I'd owe you. Thanks.