What was found
WITH CAPTAIN FLYING PILOT, FD NR 1 SELECTED, NAV & ALT MODES SELECTED, AT 27,000 FT & 250 KNOTS. BOTH CONTROL YOKES JERKED FWD & BACK APPROX 1" FOR 1 SECOND 3 TIMES APPROX 15 SECONDS BETWEEN JERKS. NO PITCH CHANGE NOTED. DISCONNECTED AUTOPILOT, DESCENDED TO 24,000 FT, ELEVATORS FELT OF POSSIBLE BINDING. RECONNECTED AUTOPILOT, NO DEFECTS NOTED FOR DURATION OF FLIGHT. ON GND ELEVATORS FEEL HEAVY PULLING AFT.