What was found
ON ROTATION FOR TAKEOFF ELEVATOR RESPONSE WAS VERY SLUGGISH AS IF A/P WAS ON IN CONTROL WHEEL STEERING. NO CHANGE IN HOW THE ELEV FELT AT 250 KIAS AND 320 KIAS. NO WARNING LIGHTS ILLUMINATED AT ANY TIME. DURING APPROACH ELEV RESPONSE FELT THE SAME FOUND CAPT AND FIRST OFFICERS VERTICAL TORQUE TUBES IN AFT FUSELAGE HAD SIGNIFICANT STIFFNESS DURING ROTATION. REMOVED VERTICAL TORQUE TUBES IAW AMM 27-31-21-4, REPLACED BEARINGS IAW CMM 27-31-38. REINSTALLED TORQUE TUBES IAW AMM 27-31-21-4. C/W MECHANICAL CONTROL AND PITCH UNCOUPLING ADJ AND TEST IAW AMM 27-31-00-5.