What was found
AFTER PUSH BACK, DURING THE BEFORE TAKEOFF CHECKLIST, FIRST OFFICER NOTICED A BINDING IN THE LEFT AILERON DURING CHECK. RETURNED TO THE GATE. REMOVED AND REPLACED THE RT OTBD AILERON PCA IAW AMM 27-11-49, PERFORMED A LEAK AND OPS CHECK, CHECKED GOOD. ACCOMPLISHED A HYD SYS CHECK WITH THE ENGINES RUNNING, EDP PRESSURE CHECKED NORMAL. THE ACFT WAS OK FOR SERVICE.