The center idler pulley was making a howling noise so I replaced and I noticed that the timing belt seemed loose. I got to the automatic tensioner and found it was not touching the belt. I pried on it was able to extend and tighten up the belt and it seems to be holding, but is there a way to determine if the automatic tensioner is defective? Does the tension on the belt change increase as the car runs? Does the tension increase with RPMs? Thank you,.