What was found
(CAN) DURING APPROACH TO RWY, FLAP 30 WAS SELECTED AND INDICATING. THE FLAP INDICATOR POSITION NEEDLE APPEARED TO RETRACT SLIGHTLY, APPROXIMATELY 1 DEGREE, FOLLOWED BY THE "EXTEND" FLAG, INDICATOR NEEDLE MOVED BACK TO 30 AND EXTEND FLAG WENT OUT. THIS CYCLE REPEATED NUMEROUS TIMES ALL THE WAY TO TOUCHDOWN. THERE WAS NO FLAPS UNLOCK WARNING, FLAP VALVE BLOCK REPLACED.