Recently, I started my car and heard rattling under the hood. I went to take a look and found the sound coming from the serpentine belt area. Turns out the tensioner pulley was shaking side to side and making a good bit of noise, like a sewing machine. I also checked the arrow indicator and the arrow was to the left of the bar, which according to this thread by AznAccord08 means I have to replace the belt and pulley.
You can see and hear the pulley in the included video. The car is at 113,000 miles now and I had the serpentine belt changed about 30,000 miles ago. Any idea how much this repair/replacement will set me back? Thanks!