I just purchased a Switchback, I have only shot it about 20 to 30 times! Awesome bow however the serving below my noc is loose and moving and I can push it down a little and see the string! What is up with that?! My bow came from the factory with the Zebra ZS twist string. I know there isn't anything wrong with the string it is the serving. Obviously something is up. However I don't know if this is a good string or not. Any advise about the Zebra string would be appreciated! Also if it is not the greatest string then what string would you recomend? Oh my draw length is 29 and 70#. I don't know if that makes a difference or not in choosing a bow string. Thanks!