Teflon tubing in nozzle throat coming out? I have a HE3D prusa XI3 printer with an MK8 extruder. While printing or testing, the extruder makes a clicking noise as if the filament isnt getting hot enough to extrude. I began my investigation and read about many reasons why this could be happening. Eliminating most of them, I finally took off the fan on the extruder and looked at it while it was trying to extrude. I noticed the teflon tubing and tried to push it back into the throat. Then the extruder worked fine. I put everything back together and began testing again. The clicking came back,  - I then took the fan and heatsink back off and there it was again. Pushing back down and this time extruding some material and noticing the tubing slowly coming up. Is there anyway to fix this without upgrading to a better hot end?
It looks like you got too tight nozzle, too cold hotend or extruding speed is too high (all could be in the same time of course).
As filament goes into the teflon tube (coldend) and then into hotend it doesn't have enough time to go out throught the nozzle. So it causes that melted filament accumulates in hotend and pushes out teflon tube.

Check application and arduino settings for 


nozzle diameter (increase it), check if it's not plugged with something inside
hotend temperature (increase it), check for your filament settings
extrude ratio (decrease it), check also gearing on extruder motor