[1crosscut]

What does the nut look like that holds the fan on. On mine someone had put a nut on that was tapered sort of like a wheel lug nut. Not being flat on the surface that contacts the fan it kept working its way into the fan wallowing it out making it loose soon after tightening it again and again. Finally figured out what was going on and replaced the nut along with the fan and all is good again.