<p>I have printed a couple weeks perfectly fine with my Ender 3. Two weeks ago I changed the firmware but the settings were all fine and resulted in good prints.</p>

<p>Now, suddenly <em>during</em> a print the extruder motor started to under-extrude.</p>

<p>I thought "hey, could be the file" and used a test file that printed well two weeks ago: Under-extrusion, barely a line.</p>

<p>I looked at the extruder, no filament grinding, no clicking from lost steps or moving against pressure. The Bowden tube is firmly seated though.</p>

<p>I measured what is coming out: instead of 50&nbsp;mm I ordered to push into the hotend got 28.7&nbsp;mm. So I went and looked at the steps/mm, which is 93, exactly what it is also on the TronXY X1, which uses pretty much the same extruder setup but for a different style, same sized gear.</p>

<p>I cleaned out the nozzle nevertheless, but that didn't change the results.</p>

<p>What might be wrong and how can I fix it?!</p>

<p>Edit:</p>

<ul>
<li>Touching the filament while I was printing a freshly sliced test, I realized it DID lose steps, just the filament did slip back (almost) quietly. Pressing a finger on the filament made me able to feel the shiver in it.</li>
<li>Inspecting what was printed showed, that the nozzle had migrated against the print platform a little over the weeks.</li>
</ul>

[{'answer_id': 6808, 'author': 'Sean Houlihane', 'author_id': 4927, 'author_profile': 'https://3dprinting.stackexchange.com/users/4927', 'pm_score': 0, 'selected': False, 'text': '<p>Sounds similar to something I experienced with my Y-axis. The grub screw on the toothed wheel had come a little loose, and I was experiencing a reasonably consistent degree of slip.</p>\n\n<p>In the extruder particularly, these locking screws might not be too obvious to check.</p>\n'}, {'answer_id': 6826, 'author': 'Trish', 'author_id': 8884, 'author_profile': 'https://3dprinting.stackexchange.com/users/8884', 'pm_score': 3, 'selected': True, 'text': '<p>A close inspection of what happened when printing the first layer resulted in this:</p>\n\n<ul>\n<li>The missing steps on the new print came from the nozzle scraping too close to the print surface, which lead to no first layer</li>\n<li>Readjusting the Z-axis end stop, which had moved down, resulted in no more lost steps, but the print not sticking for the first test.</li>\n<li><p>Releveling the bed and making sure the bar was parallel to the bed resulted in a perfect first layer.</p></li>\n<li><p>Lost steps and under-extrusion could not be replicated after 48 hours of <em>rest</em> for the printer.</p></li>\n</ul>\n\n<p>I have no idea why the print had failed due to under-extrusion <em>during</em> the print, but apparently, my immediate tests were flawed enough to not detect the first layer height resulting in getting almost no extrusion. This I mistook for massive under-extrusion, making me believe something else was at fault.</p>\n'}]
['https://3dprinting.stackexchange.com/questions/6807', 'https://3dprinting.stackexchange.com', 'https://3dprinting.stackexchange.com/users/8884/']