What was found
AFTER TAKEOFF AND AT FRA CALL THE SIC TOLD THE AIRCRAFT WOULD NOT TRIM AND BE WAS HAVING TROUBLE KEEPING THE NOSE DOWN. RAN THE PRIMARY STAB TRIM INOP CHECKLIST. COULDN'T GET SECONDARY STAB TRIM TO WORK EITHER. REMOVED FAULTY ACTUATOR CONTROL UNIT. INSTALLED OVERHAULED CONTROL UNIT. COMPLIED WITH SATISFACTORY TESTS OF PRIMARY & SECONDAY TRIM ACTUATORS IAW MM 27-40-00. RECOMMENDATION LOOSENED THE TENSION ON CHAIN CONNECTED THE PRIMARY & SECONDARY STAB TRIM ACTUATORS. PERFORMED OPS CHECK WITH NO FAULTS. WORK DONE IAW AMM 27-40-00.