Verify that the filament_sensor_lever and the filament sensor pocket on top of the extruder_body do not have any strings and are printed well. Clean up if necessary.

Insert the longer magnet (20x6x2mm) inside the filament_sensor_lever.

Place the smaller magnet (10x6x2mm) so it is attracted to the filament_sensor_lever. The smaller magnet should be on the flat side of the lever.

Remove the smaller magnet from the filament_sensor_lever and insert it with the same orientation into the extruder_body. DO NOT insert the filament_sensor_lever yet.

Verify that the smaller magnet is fully inserted into its cavity.