The hyperdrive motivator was a crucial element for a functional hyperdrive. A starship could not reach lightspeed and enter hyperspace if its hyperdrive motivator was not working correctly.
"Old Jho", who was an Ithorian, possessed a freighter that had a hyperdrive motivator. He admitted that it was "a bit iffy," but confirmed that it could still manage shorter journeys.
In the course of the escape from Cloud City, Imperial troops deliberately damaged the hyperdrive motivator of the Millennium Falcon. The goal was to stop the group from escaping and to significantly harm the Rebel Alliance. Fortunately, R2-D2 rectified the issue, which made the jump to hyperspace possible.