Make sure the printer and power supply are off and unplug the power supply from the printer.

Remove any filament from the extruder assembly.

Unplug the pin harness.

Using a 2.5mm hex key, remove the M3 screw securing the extruder assembly to the carriage plate.

• Reinstall the screw into the insert on the carriage plate to keep track of it for reassembly.

Lift the extruder assembly up and off the carriage.

Using a 1.5mm hex key, remove the M2 screw securing the old blower fan.

Using a 2.5mm hex key, remove the four M3 screws securing the layer fan to the layer fan shroud.

• Once removed from the shroud, keep the screws in the layer fan for reuse during reassembly.

Using a 2.5mm hex key, remove the two M3 screws securing the layer fan shroud to the extruder assembly.

• Reinstall the screws into the inserts on the extruder assembly to keep track of them for reassembly.

Using a 3mm hex key, remove the two M4 screws securing the hot end plate to the extruder assembly.

• Make sure to keep these screws in a safe place as they will be reused for reassembly.

Once the screws are removed, everything should come apart as shown.

Remove the following pins from the extruder assembly-side wiring harness:

• Pins 5 & 6: Heater cartridge
• Pins 9 & 10: Blower fan
• Pins 15 & 16: Thermistor

Pin diagram from Lulzbot's documentation: http://download.lulzbot.com/TAZ/5.0_0.5n...

With the pins removed, the harness should now look like the first picture shown.

Clip off the zip tie holding the wires together and remove the old hot end and blower fan.

Take one of the four screws from the layer fan and screw it in to one of the inserts, leaving enough length to grip it with a pair of needle-nose pliers.

Heat up the screw with a soldering iron and apply upward pressure with the pliers until the insert comes out.

Repeat for the other three inserts.

Place one of the four inserts you removed in the previous step over one of the holes on the new layer fan shroud.

Insert the soldering iron straight down into the hole as shown in the first picture and apply downward pressure until the insert sinks into place.

• Be careful not to press too hard or you risk sinking the insert farther into the hole than it needs to go.

Repeat for the other three inserts.

Cut the wires 125mm from the top of the heat sink fan as shown.

Strip 4-6mm off the end of each wire.

Crimp the Molex male terminal pins onto each wire.

• The pins have two sets of tabs. Use a set of needle nose pliers to fold the inner tabs over the bare wire. Fold the outer tabs over the insulation.

For extra security, solder the pins onto the wires.

Install the pins according to the pin diagram from earlier:

• Pins 5 & 6: Heater cartridge
• Pin 9: Blower fan red
• Pin 10: Blower fan black
• Pins 15 & 16: Thermistor

Pin diagram from Lulzbot's documentation: http://download.lulzbot.com/TAZ/5.0_0.5n...

Fit the new plate around the top of the hot end as shown.

Insert the hot end and extruder assembly into the carriage plate as shown.

Fit the top of the hot end into the circular indentation on the extruder assembly and reinstall the two M4 screws from earlier.

Install the new layer fan shroud using the two M3 screws you saved from earlier.

Wind the layer fan wires around the other hot end wires and reinstall the layer fan using the four M3 screws you saved from earlier.

With the layer fan installed, the extruder-hot end assembly is complete.

Remove the four M3 screws securing the access plate to the control box.

Remove the two-pin connector from its socket on the RAMBo board.

Remove the pins from the harness.

Cut the large end off of the connector pins.

Remove the main power wire block from the left side of the RAMBo board.

Loosen the screws on the red and black terminals at the end of the power block as shown.

Insert each fan wire into its respective power block terminal (i.e. red to red, black to black).

Tighten the screws firmly to keep the wires in place.

Reinstall the power terminal block into the RAMBo board.

Reinstall the access plate with the four M3 screws you removed during disassembly.

Reinstall the extruder-hot end assembly back onto the carriage with the M3 screw you removed during disassembly.

Reconnect the two pin harnesses.

If necessary, turn the heater block so that the long end does not protrude toward the front of the printer.

Plug the USB cable into the printer.

Plug the other end of the USB cable into the computer.

Plug the four-pin power supply connector into the printer.

Plug the power supply into a wall outlet and flip the switch to the 'on' position.

Everything's connected. Flip the printer's power switch.

• The LCD screen should show the normal boot sequence and the E3D hot end heat sink fan should start spinning.

Follow the PID tuning guide to calibrate the new hot end.

Connect the printer to MatterControl and set the extruder temperature to 260°C.

Using a 7mm socket wrench and an adjustable wrench or tongue-and-groove pliers to hold the heat block steady, tighten the nozzle.

Unscrew the thumbscrew almost all the way up.

Home the Z axis.

Depending on how far the nozzle is from the bed, screw the thumbscrew down a turn or two at a time.

Repeat homing and adjusting until the nozzle is the distance of a paper's thickness away from the bed.