To see how the calibration is, we must observe that the mark of the laser beam is in the center of the hole in the laser head, if the two marks overlap but are above the center, it means that the height of the tube is above of the height of the laser head and the tube must be lowered.
Set the maximum power to 30%, put a double layer of masking tape on the hole of the laser head, and press the pulse button on the operation panel of the machine
Note: look at the silhouette of the head hole, it must be centered with respect to this