I use a v6 with a Bowden tube and have noticed for a while that the little black plastic ring that secures the Bowden tube will be up most of the time but it does get pushed down during retraction. This means that there is normally a space between the Bowden tube and the metal heat break inside the heat sync during extrusion. I have noticed more jamming lately and suspect that the tube is getting looser than normal. The Teflon Bowden tube does have a dent where the ring goes and I suspected that the dent is getting larger. I have cut about a cm off the tube to allow it to grip a new part of the tube. I have also wedged a spacer between the black ring and the heat sync to keep it up all the time even during retraction. Has anyone else looked into this to see if it could help reduce jamming? I have had good success so far, but I also changed the thermister profile from epcos to semitec and I am not sure what change is making the difference.