At about 1600 eastern time, a Stinson 108 was damaged while landing at White Post Airport. The pilot was not injured. The pilot said he had just completed an annual inspection of the airplane and had also overhauled the engine. After a normal takeoff, he returned for landing. As he added the final notch of flaps, he said he heard a ping and the airplane dove toward the ground. He was unable to arrest the descent and the airplane hit hard and nosed over. An FAA inspector found that when the control yoke was moved through its full range of motion, it struck the radio rack, which restricted its rearward motion.