Stepper Question (Newby)

He everyone. I have finally got my Taig Mill hooked up using the
Stepperworld FET-3 and 150oz stepper motors. Everything seems to move
correctly however I can very easily hold the other end of the motor
shaft to stop movement. The motor seems to hum as if something inside
is moving but the shaft is not.

Anyone have a clue as to whats happening. I don't think that I should
be able to stop a 150oz stepper motor that easily.

Help,

Alan Trest