If things are not moving, don't leave the voltage up for very long. Bad things can happen! Meanwhile, probably time the look at the brushes, clean the commutator (where the brushes touch), change the grease on the worm gear (you have to take the brush plate off, which may require unsoldering a wire) and the reverse unit (E-unit). For the E-unit, it is best to find someone who has done this before.
Chris
LVHR