I understand why the locking tool caused the bent hex bolts on the pulley -- it is just too tight. The looped belt trick is better then the locking tool, because the pulley has the much bigger radius than the 4-bolt circle, and locking torque is directly proportional to radius, as Sir Newton said years ago.The damage was resulted from being under the impression that I needed to give it more force. As soon as it cracked and I saw the bolts bent I went to trying the hex screws inside the fan.