Well, the "Stabilizer wheel - grasp and hold" item of the procedure doesn't necessarily mean the crew will be able to override it. That's the last ditch option

Well, the "Stabilizer wheel - grasp and hold" item of the procedure doesn't necessarily mean the crew will be able to override it. That's the last ditch option on the checklist, when everything else has failed, even turning the motors off (there could be e.g. a short circuit powering the motor). There is no clutch on the 737, AFAIK, because the forces are such that it wouldn't work. Here is a good video by an actual 737 captain explaining how the runaway stab trim procedure works and what you have to do. https://www.youtube.com/watch?v=xixM_cwSLcQ https://www.youtube.com/watch?v=xixM_cwSLcQ And this simulator video shows both how the 737 horizontal stabilizer is controlled and what kind of forces are on the trim wheel and control column when severely out of trim: https://www.youtube.com/watch?v=aoNOVlxJmow https://www.youtube.com/watch?v=aoNOVlxJmow Should give you an idea what were the Ethiopian pilots facing when unable to use the electric trim, plane trimmed nose heavy by MCAS and at high speed ...