Hi folks just joined landyzone, got a problem, went to change serpentine belt used a 24mm ring spanner turning anti clock the hexagon just keeps turning but the tensioner does not slacken off, my haynes book calls the hexagon a bolt but it looks like a nut, in the center is a threaded hole looks like rt hand thread?, is something missing out of the thread or do i need a new tensioner, this is the first time this job as been attempted on my car i think a nother member else has had this prob in the past thanks in anticipation.