Sometimes filament can get stuck in the filament guiding system. The tutorial below explains how to bring it back to work again.
WARNING: Be careful not to damage the cables for motors and heaters. If unsure, perform all the steps below with power switched off, then switch it on, heat up the nozzles and keep them heated only for filament pushing.
Heat up clogged nozzle to a filament temperature.
Remove the plastic part on the right, that holds the cooling fan in place. Remove the 4 long screws holding the motor unit, as below. To see the parts better, also remove the fan (black part in front).
Move the right motor out from the extruder.
By now, you should clearly see the filament guiding system and entry point (note the black arrow below).
If you see the end of the filament (you should be able to), grab it with pliers and pull gently. Be careful not to break it, as it will be more difficult to pull the remaining part later.
If the filament is broken and can't be pulled, the only way to make it work is to push it even further. To achieve that, you need rigid and thin element below 2 mm in diameter. A small hex key is usually good for that – you can find one in the ZMorph set. Insert it gently (while nozzle is hot) from the top, and push. After a while you should see the filament flowing through the nozzle. You can then continue pushing with different filament, to make sure it works correctly.
After pushing the filament through, mount the motor unit back and secure it with 4 remaining long screws.
Regulation of the filament feeding wheel might be necessary. Do some tests and adjust the wheels pressure by loosening and tightening the screws.
Switch the machine off and on to complete the process.