Before replacing the actuator, make sure it's not just a stuck pin in the shock. You can pull the actuator and see the top pin that the actuator rotates.
Note the position of the pin and then using a needle nose pliars try to turn it. It should turn freely. If it doesn't, spray some penetrating fluid down there and work it back and forth until it moves freely.
Put it back in the position it started with and reattach the actuator. See if works o.k. now.