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The printer is showing the message: "Failed to home the extruder in Z-axis, make sure the loadcell is working".
Error name: Homing error Z
Error code: #31301 (CORE One) #35301 (CORE One L) #36301 (CORE One INDX) #26301 (MK4S) #13301 (MK4) #27301 (MK3.9S) #21301 (MK3.9)
Make sure that the extruder is not exerting force to pull down the filament. If you are not sure, try to unwind it a small amount on the spool when testing the Z-axis.
In case you have an MMU, Enclosure, or custom setup where the filament is fed to the extruder by a PTFE tube, make sure that the extruder does not have to exert force to pull down the tube.
On CORE One and CORE One L, move the bed down, open the trapezoid nuts, and check if they can move freely along the threaded rods.
It is also possible to lubricate the Z-axis lead screws as instructed in Regular printer maintenance (CORE One/+) under "Axes check - Z-axis leadscrews"
 |  |  |
| Rear motor | Front left motor | Front right motor |
If your CORE printer is equipped with the INDX, check also that the spacers are correctly installed.
 |  |  |
| Left spacer | Rear spacer | Right spacer |
On MK-series printers, check if the trapezoid nuts have the correct orientation.
If the above checks do not solve the issue, it will be necessary to troubleshoot the loadcell and the components surrounding it. The dedicated loadcell troubleshooting article contains all the points to check, and that can be related to this error.
14 comments
The loadtest sensor passes the test.
I noticed during Z homing (and the Z axis test) that the nozzle would be ~1mm above the bed at minimum when the build plate would be at the top.
I lowered it slightly to see about 2mm of the copper above the heatbreak, which fixed the homing error.
was solved, by :
1- Move axis z to the bottom
2-auto Home
3-Z axis Calibration