What was found
WHILE ACCOMPLISHING LEAK CHECK OF #2 ENG FUEL FILTER, FOUND FUEL LEAKING FROM FUEL HEATER SERVO COVER. GROUNDED - YES. REMOVED AND REPLACED O-RING ON #2 ENG FUEL HEATER SERVO REF CMM 73-11-77, LEAK CHECK FAILED. FUEL NO LONGER LEAKING FROM SERVO COVER O-RING. NOTED LEAK FROM PREFORMED PACKING ON CENTER BOLT FOR SERVO COVER. REMOVED AND REPLACED O-RINGS ON SERVO COVER AND CENTER BOLT. PER CMM 73-11-77 AND B737-800 AMM 73-11-07. OPS TEST NORMAL. LEAK TEST GOOD.