Cabrio Belt Tensioner
 

I just had to replace my alternator in my 2000 Cabrio. After I got the new alternator in, it was obvious that the belt is too tight. The tensioner system is a pulley wheel attached to a large spring, which has a cap over the spring. I cannot for the life of me figure out how to loosen the tension on the belt. Any assistance to this effet would be most greatly appreciated. Thanks!