At 12:55 eastern time, a Cessna 210 was damaged during landing at Newark-Heath Airport following an apparent loss of elevator control. The pilot and passenger were not injured. The pilot was descending at the end of a cross-country trip when he noticed he had to use both hands on the yoke to stop the descent, even with full nose-up trim. When he flared to land, he could not get the nose to come up and the airplane porpoised. Inspection showed the control column stop was chafing on the rear casing of the HSI. Five shock mounts were installed on the instrument panel, of which the lower right and lower center shock mounts were broken, and the upper left shock mount was not attached.