You'll need to replace the the PTFE/Teflon sleeve with a fresh one:
And once the new section of PTFE/Teflon sleeving is inserted, it should look like this:
The next thing you'll need to do is to clean off any debris from the threaded portion of the extruder tube. In addition it's always a good idea to clean off any significant debris from the brass extruder nozzle, and see if it might need to soak in some acetone for a while prior to being joined back to the extruder tube.
In most clog conditions, you'll be able to re-use the brass extruder nozzle straight away, but for sever clog situations, you may wish to soak the nozzle in acetone for a few hours (or even overnight) to soften any molten filament remains. This is why it's not a bad idea to have a few spare extruder nozzles (contact AIO for pricing and availability), as having spares will enable you to get back to production more quickly.
If you didn't laugh too hard at the suggestion of getting a 0.013“ guitar string, then this is time to carefully poke it through the brass nozzle aperture to completely clean any remaining debris:
Now you'll want to manually thread the brass extruder nozzle on to the stainless steel extruder tube and rotate it until it reached the top of its possible travel. Finger tighten it so that no threads are exposed and then using the appropriate tools, further tighten the brass nozzle. Do not over-tighten!
Make sure that no threads are showing:
After putting the extruder tube sub-assembly together (comprised of the stainless steel extruder tube, the aluminum heat sink, and the brass extruder nozzle), the next very important step is to thread the hexagonal thermocouple back into the brass nozzle so that you can hold it stationary and then rotate the extruder tube sub-assembly against/around it.
This is essentially the reverse of the step in the dis-assembly process, and requires the exact same attention to making sure to handle the hexagonal thermocouple, and especially its wires carefully so that they do not get twisted.
Now we're in the home stretch…
The heater element should slide back in easily, however if it there is baked-on filament debris on it, then you may need to carefully scrape the debris off, or possibly use some fine sandpaper or 00 or 000 steel wool, but it's pretty rare that you'll need to do that.
The important thing is to pay attention to is actually how the heater element is seated; it needs to be essentially flush with the side of the brass extruder nozzle on the side where the hexagonal thermocouple is mounted:
Okay, we're in the “home stretch” now, and the rest of this is really very easy (not that much of it is all that challenging, once you know what everything is…)
The first time you go through this process, it may seem complex and tedious, but after you've done it once or twice, you 'll probably be able to do it in under 10 minutes, and it will become quite simple
Click on the link below to go that section: