Do-It-Yourself Story

I initially thought is was a fan motor going bad so I replaced it yet the noise continued. I ordered a new fan blade, although the existing fan blade seemed fine. What I found out is the fan has to be really tight on the spindle that turns. The old fan blade center hole must have enlarged just enough over the years that when the fan would kick into high speed it would produce the aggravating noise. The new fan blade was very tight to put on and immediately the noise was now a quiet purr.