⬢Open the upgrade package and look for a bag with the new (shorter) PTFE tubes.
⬢Check the new PTFE tube. Make sure both ends are clean.
⬢Now it is time to insert the new PTFE tube. Note there are two different ends:
⬢One end of the tube has a "rounded" outer edge. This end must be inside the hotend.
⬢Look at the other end, where the tube is drilled inside, the shape of the edge is "conical". This is the side, where filament enters the tube. This part must be outside the hotend.
⬢Push the black collet in. Slide the tube all the way in and hold it!
⬢Using second hand pull the collet out and only then release the tube!!! THIS IS CRUCIAL for the hotend to work properly. The tube must not be able to move in or out!