Tensioner troubles

I have a 94 Beretta with the 3100 v6 engine. Recently I found my serp belt shredded. I started to check things out and found the tensioner was sticking way out far from the block and was loose to the touch. I can see the coil and that is also loose to the touch. Does anyone know what would cause the tensioner to pop off the block and for the coil to be loose ?

14 years of use.

I purchased a new one mfg. by Dayco at Advanced Auto for my wife's Malibu.