Hi, I have a troy bilt 17.5hp 42'' deck riding lawnmower. Today when I was cutting the grass I disengaged the PTO lever to back up and when I went to engage it again nothing happened. There is no tension in the lever at all. All the belt are on but not tightening. Is there a electronic cut off or something that is keeping the belts from tensioning? Any help would be appreciated, there are only 3 days left on the 1 year warranty.