What was found
AFTER TAKEOFF, FORWARD 2 EXIT LIGHTS AND AISLE EMERGENCY LIGHTS IN FIRST CLASS AND FIRST 3 ROWS OF CABIN WERE FLASHING, THEN ON STEADY. CYCLED COCKPIT EMERGENCY LIGHT SWITCH OFF, THEN TO ARM BUT NO HELP. LIGHTS EXTINGUISHED 20 MINUTES LATER. REPLACED FORWARD (10WL) EPSU, TESTS OK.