first off that serial number you give is incorrect, the first digit should be a letter , not a number.
second, the steer motor is mounted underneath the floorplate as was said previously on the left side.
thirdly, if you go banging on it with any kind of hammer you risk damaging the motor, these are permanent magnet motors and banging on them will only run the risk of dislodging a magnet or breaking one, then you will be replacing a motor assembly instead of just putting brushes in one.

which brings me to the solution most likely in this scenario
if you have full contactor actuation and voltage is present across the contactor, make sure the fuse(s) are not blown, there should be two (40A) fuses in the rear panel both linked together on the bottom two sockets of the fuse block for the control fuses. If these fuses are blown they HAVE TO BE SLO BLO FUSES, nothing else will hold up. If no problems found there then the problem is most likely the brushes in the steer motor.
You will have to remove the screws holding the motor cover on the sides and look in there and see if they are worn out.