1. Refer to Section 3.1 to take the nozzle assembly off the extruder assembly. Figure 3.2 - 1
2. The whole nozzle can be divided into 3 portions: nozzle, top cap, throat & hot end assembly (Figure 3.2 - 2). Separate them by a monkey wrench and replace them as needed.
3. Notice that there is a Teflon tube inside the throat, check if the new throat has this Teflon tube before assembling the nozzle.