I HAVE A 235 AND THE DRIVE PULLEY APPEARS TO BE FROZE UP. IT IS THE PULLEY WHICH SITS ON THE BOTTOM OF THE MOTOR. ENGINE STILL RUNS FINE BUT TRACTOR WILL NOT MOVE. I CAN FORCE THE PULLEY TO TURN WITH MY HANDS AND A LOT OF PRESSURE. WHAT DO YOU GUYS SUGGEST IS THE PROBLEM AND THE FIX. THANKS, BRETT