Make sure all the packing is out of the back of the clock.  Open the back plate of the clock and pull out the orange clips on the bellows and check for packing around the chime rod.

Look at the front of the clock and make sure the wire is not holding the bird door closed. If the wire is over the door just slide the wire to the side so the door can open. 

Check to see if the clock has a lever to turn the cuckoo on and off. The lever may be on the bottom of the clock by the pendulum or on the side of the clock.  If the lever is on the bottom of the clock it is a push n pull lever. If the lever is on the side of the clock you can slide the lever up and down. Try the lever in both positions to see if it starts to cuckoo.