If you're print head looks like a plastic caked on mess then this tutorial is for you! Grab some allen keys, a philips head screw driver and lets get started!
Step 1: Gather Tools and Replacement Parts
2.5 mm Hex
Fargo 3D Heater Box Replacement Kit
Step 2: Remove Filament and Turn Off Makerbot
Go to Utilities>Unload Filament this will begin the heat cycle on the Makerbot Replicator 2. Once the nozzle is up to temperature pull off the filament guide tube and pull out the filament.
Turn of Makerbot
You can choose to either cool down the Makerbot by using the cool down function in the utilities menu. The advantage here is being able to know for sure when the nozzle is cold. Or, you could also just unplug the Makerbot and wait 10 minutes.
Step 3: Remove Fan & Heat Sink
Using a hex key unscrew two long bolts holding the fan cover, fan, stand offs and heatsink.
Step 4: Unplug Stepper Motor
Carefully pinch the connector and gently pull upwards to remove the cable.
Step 5: Remove Printer Head From X/Y Carriage
Unscrew Carriage Bolts
I recommend using supplement light to help illuminate the underside of the print head. This really helps in locating the two hex bolts holding the printer head to the X/Y carriage. Unscrew these bolts and be super, super careful pulling off the carriage head.
Step 6: Cut Cable Zip Tie
Carefully cut the zip tie holding together the wires going to the printer head
Step 7: Remove Blower
Using a Philips screw driver unscrew the blower from the printer head let all the components separate. Taking a picture here for reference would be a great idea for later reference.
Step 8: Unscrew Aluminum Block Assembly
Grab your allen key and unscrew the blower fan from the block assembly. This step is really about removing all the plastic components from the aluminum block. Pay attention to which side the screw holes are located on the aluminum block relative to the front of the machine. Reassembly will require everything to be accurately positioned.
Step 9: Remove Heater Cartridge
Unclip the heater cartridge connector, then unscrew the hex set screw and pull out the heater cartridge. Mine was super dirty so I did some gentle coaxing with a heat gun and some pliers. After the cartridge was removes I cleaned off as much of the burnt on plastic residue as I could with an xacto knife, being careful not to damage the actual body of the cartridge.
Step 10: Remove Heater Block From Aluminum Block
Unscrew Retaining Nut
Grab a pair of pliers, you're going to need one to hold the block and and one to unscrew the nut holding the heater block assembly.
BE SUPER CAREFUL NOT TO BEND THE THERMISTOR CABLE
If you bend the thermistor cable you will need to order a new thermistor you cannot bend it back.
Step 11: Remove Thermistor
Carefully remove the thermistor by unscrewing the heater block and keeping the thermistor stationary. Grab your new thermistor from the kit and pat yourself on the back you :) Lets get ready to reassemble the entire thing.
Step 12: Replace Thermistor & Heater Cartridge
Screw in the thermistor by rotating the heater block.
Step 13: Reassemble & Heater Tape
Now go ahead and reverse these steps, reassembling the 3D print head. Before putting the carriage bach on to the Makerbot go ahead and add the heater tape around the aluminum extruder block. Reattach and print a test part to make sure everything is still working properly!
Congrats on finishing this tutorial and happy printing!