What was found
FLT 735 JFK-BQN, AIR RETURN TO JFK DURING CLIMBOUT APPROX 17,000 FEET FELT MODERATE VIBRATION THROUGHOUT ENTIRE AIRCRAFT. TURNED OFF AUTOPILOT APPLIED LIGHT PRESSURE TO RIGHT RUDDER. PERFORMED BACKLASH CHECK AND REPLACED RUDDER SERVO CONTROL 1025GM, 2025GM, 3025GM. ALSO REPLACED ELEV SERVO 34CE4, 34CE2 & 34CE1. OPS, LEAK AND RIGGING CHECK OK.