What was found
FUEL IMBALANCE ON GROUND. LEFT WING HASS 300 LBS LESS THAN RIGHT WING W/ FUEL IN CENTER TANK. FUELER REPORTED "LEFT WING TANK WOULD NOT TAKE THE FUEL TO MAKE IT EVEN". GROUNDED - YES. REVERSED MEL 28-6B MAINTENANCE PROCEDURES. PERFORMED FQIS SYSTEM TEST REF B737-800 AMM 28-41-00-730-801, #1 TANK NOT WITHIN LIMITS. PERFORMED RANK AND COMPENSATOR UNTIS RESISTANCE AND CAPACITANCE CHECK REF AMM 28-41-21-710-801. FOUND COMPENSATOR F15L, AND PROBES F2L AND F5L OUT OF LIMITS. INITIATED MIG-2C 40-0045118. REMOVED AND REPLACED #1 TANK COMPENSATOR F15L, AND PROBES F2L AND F5L REF AMM 28-41-21. ALL PROBES AND COMPENSATOR NOW WITHIN LIMITS. COMPLETED MIG-2C 40-0045118. LEAK CHECK GOOD. FQIS SYSTEM TEST PASS REF AMM 28-41-00-730-801.