What was found
AT CRUISE NOTICED #1 FUEL TANK DECREASING RAPIDLY (1200 LB IMBALANCE). DIVERTED TO PSP. NOTICED 2 UNITS LEFT AILERON TRIM. NO OVERWEIGHT LANDING. ON POST FLIGHT INSPECTION (WITH FIRE DEPARTMENT); NO VISIBLE INDICATION OF A FUEL. FINAL IMBALANCE AT THE GAGE WAS 1300 LBS <[01]. OK TO CONTINUE PER MEL 28-6-01. SP1 AND SP3 C/W. AUTHORIZATION #255474.; [02] TANK 1 COMP IS OUT OF LIMITS PER AMM 28-41-21; [03] R&R #1 TANK COMP. OPS CHECK GOOD. REVERSED SP#1 & SP#3. REF TANK TIGERS W/O# TT01787. THIS CLEARS THE MEL. WORK PERFORMED IAW B737 AMM 28-41-21.