In the early 1980s a problem was found with the 737-200 model. When the elevator operated to raise or lower the nose, it set up a strong force on the trim jackscrew that opposed any corrective force from the control systems. When attempting to correct an unwanted deflection using the manual trim wheel, exerting enough hand force to overcome the force exerted by the elevator became increasingly difficult as speed and deflection increased and the jack screw effectively jammed in place.[98]