I've had my fan off and on my blower motor a couple of times. The fan appears very strong. All I used for tools were a hammer a punch the size of the motor shaft and a workmate bench.

First remove the plasic housing from the rear of the motor. Open the workmate bench just enough to slip the motor through but not the fan. The fan should now be resting on the bench with the motor hanging underneath. Now measure how far the motor shaft is prodruding from the top of the fan. You will need this measurement when you reassemble the fan. Hit down on the motor shaft to release it from the fan. It may seem that nothing is moving but continue to hit down on the shaft. It will eventually move. Use the punch to drive the saft through the fan hub. Make sure to catch the motor as it falls away from the fan.

To reassemble reverse the procedure. Place the fan face down on the workmate bench. Start the new motor with shaft into the hub of the fan. Use a hammer with a block of wood or bronze and hit down on the motor shaft at the brush end of the motor until the shaft is through the fan hub. Make sure the shaft is prodruding from the fan hub the same amount as before.

This method worked well for me and after taking the motor apart and cleaning and lubricating the motor bushings my blower is working like new.