Stage 14 (The Necromancer): The keep's interior | Walkthrough LEGO The Hobbit Guide

The mechanism that you eject the stairs with

Of course, start by smashing the objects in the area. This will allow you to find a Dwarf Axe, which you are going to need in several minutes (the weapon can be used by any of the characters)/ On the left, there also is a Save Statue, although you do not need to activate it. Explore the left side of the location and, after you demolish it, hold down the building key/button. wait until a rotary mechanism is built and interact with it, in order to slide out the stairs to the upper-left balcony.

The place where you put the knob in place

Climb up the stairs, to the balcony on the left. Destroy the cage with skeleton here and examine the remains, thanks to which you will obtain a knob. Approach, with the knob, the nearby mechanism, click it into the slot and use it straight away. This will slide apart the grates to the exit from this location.

You will reach the shelf with the second knob, by grabbing the ledge

Jump down and explore the right side of the room. Here, you need to use the axe that you have just obtained, to smash the cracked plate. Hold down the building key/button now and jump onto the shelf that you have built. You can now jump towards the balcony on the right, and towards the edge on the wall. Shimmy to the left and jump over to the ledge with another knob on it, which you need to interact with. Do not expect that you will be able to leave this location straight away, because Azog, and his minions, will enter here.