See the screw on the side of the steering, can be unscrew by using an allen key..
Front view of the steering, this is the model with air bag...
Look like this after i unscrew both of the screw.... Remove the horn...
There're wire connected between the horn to the steering base, use a plier the bend the metal bracket on the both side until it suit balance for the left and right...
Screw back the horn... Press your horn to check... Adjust again if left or right cannot press smoothly....