There are two different possibilities:
Loose minute hand and loose hour hand
If your minute hand is loose, tighten up the screw visible from the front. Then drive the hand to the full hour and synchronize the cuckoo call with the time. Synchronizing guides:
The cuckoo is desynchronized - doesn´t call on full and half hour, but at other times.
The cuckoo call the wrong time - for an example 5 times at 7 o´clock.
If your hour hand, turn minute hand to the full hour, count the cuckoo calls and position the hour hand correctly. Once in correct position push it slightly inwards.