The number one inconvenience that you will run across when 3D printing is clogging of the extruder. But we have good news for you! -these problems can be easily avoided by following a few simple rules of "3D printing etiquette".  

When unloading or changing the filament:  always heat up all the way first and then "extrude" for 5 seconds and immediately "reverse" aiding the filament retrieval by pulling a little bit on the filament end going into the extruder with your hand.

If the extruder is clogged, clean out the passage way of the extruder.  You can use the small allen wrench which comes with your CraftBot to do so.  Heat up to 250°C while the extruder is empty and push any excess filament out by plunging the allen wrench down into the passage way; make sure to do adequately but not in a violent way which would damage the machine, and always take precautions because the extruder is very hot! 

It is especially important to clean out as much old filament leftover between using different filaments, as the different characteristics of the filaments’ properties (even printing the same material in a different color) can cause clogs from inconsistencies.  For example: you must heat up to 250°C to clear out any extra ABS before using PLA.

Clogging is the most common problem in every 3D printer and cannot be prevented 100%, but if you follow these simple steps you will prevent 95% of occurrences.

If you still cannot clear the passage with just this method, you may want to move onto the next method by following these next steps to actually remove the nozzle itself…

To clean out the extruder properly by removing the nozzle... you will need to remove the nozzle while heated up to 250°C using both a 7mm and 11mm wrench for the two nuts located on the nozzle itself and the channel end to the top side of the extruder  -make sure to use an oven mitt to protect yourself from burns.  You will also need to disconnect the fan assembly and remove the entire piece by unfastening two bolts connecting it to the top of the extruder.  most importantly, make sure to hold the red rubber part stationary at all times so that you do not damage the wires running into it, you can use a wrench to do so; if the wires snap off you will be in a real mess, so take the necessary precautions!  After you get the nozzle off you will have better luck unclogging using the method recommended in the previous text; you can also clean the nozzle with a pin and gas (either on a lower heated torch or a gas stove), or you can just replace the nozzle which is suggested from time to time anyhow for optimal printing.