No i don't think so.
I suspect a the head motor completes the circuit similar to an open collector circuit.
If you have no head operation, either try another known working head, clean all connection points and carry out a continuity check between those connections and the head motor connections.
In the past i have had a couple with similar faults, the hand units output had failed and is not serviceable as far as i know.
There are a few checks you need to do before condemning the hand unit.
I would test the motor first with an external voltage source if possible and a continuity check to the head assy (and clean connectors)