In fact, there was a Teflon hut in the hotend. It shrunk quite a bit at the end, about 0.3 mm to be exact. If you run your fingers along it, you can feel how it tapers off considerably. The sleeve is also totally clogged. Can I shorten the shrunken end and put it back into the hotend or does the sleeve have to be as long as the hotend? Can I purchase these sleeves separately or buy the component directly?How can this actually happen, I mean I have printed within the given framework conditions released by the manufacturer.Many thanks for your help!