1. Take exturder assembly off the machine.
2. Remove the 4 screws on 2 sides of extruder assembly with 2.0 mm Allen-Key, and remove the black cover. Figure 3.3 - 1
3. Disconnect 3 cables on the PCB, and remove the 3 screws with a cross driver. Figure 3.3 - 2
4. The PCBs on left and right extruder assemblies are the same, they can be swapped.