My rear wheels on this mower will not turn. The gear box which turn the rear wheels works and the axle turns but the pawl inside retainer drive is not engaging inside the the wheel part to turn the gear. I do not know if it is just the torsion spring which makes the pawl move or if it more parts I need in the wheel gear assembly part like disc drive or friction seal. This is a craftsman 6.5 hp rear wheel drive. model no. 917.377840. Anyone have a lawnmower like this and ever had this problem? I do not want to buy a bunch of parts I do not need just guessing..would appreciate some help.