What was found
LANDING GEAR FAILED TO RETRACT, TRIED BOTH SYS 1 & 2. RETURNED TO AIRPORT. ACFT DOWN FOR WORK. REMOVED AND REPLACED PROXIMITY DETECTOR PROCESSING UNIT PER MM REFERENCE 32-31-71-4. BDL/11, LUBRICATED PIVOT PIN AIW MM 12-22-32-0 - BDL/11, ACN RELEASED FOR SERVICE PER MEL/CDL: 32-30-01. JACKED ACFT AND SWUNG GEAR SEVERAL TIMES. ALL THREE LANDING GEARS RETRACT AND EXTEND NORMALLY IN 1&2. DISCONNECTED PITCH DAMPERS ON BOTH MAINS TO CHECK FOR MOVEMENT OF BOGIES. NO BINDING NOTED. MM 32-11-15-4. RECONNECTED PITCH DAMPERS AND CHARGED SYSTEM PER MM 12-12-32-0. OK FOR SERVICE.