I received again that old error:

{'code': 'key526', 'msg': 'PR_ERR_CODE_HAVE_LOST_STEP: Z-axis motor step loss was found.', 'values': ['RUN_G29_Z check last point res_z:(3.09153125) out of lost_step_dis:0.5']}

But this time none of the suggestions I found in the Internet helped me to fix the issue.

I found this suggestion from “CougarNyht” in the Youtube from a guy that fixed the issue in the K1 Max printer.

You do not need to remove the side panel. Home to Z Axis first. Then adjust via removing the bottom cover and release tension from belt to remove and then using very small movements the front right and front left Z screws. Then reattach the belt and do the self-alignment and check the bed mesh. Repeat the process until within 0.2 parameters. Using spacers puts improper stress on the bed connection points. If your bed is actually warped then replace it and do the correct process for absolute Z balance point.

Then I decided to do a different approach, after Homing All axis I move the Head to the front of bed (near the door and move the bed to barely touch the noose (I use a thin card to fit exactly between the bed and the noose, so I can move it and feel just a little bit of friction).

Then I noticed then I tried to move the Head the the back of the bed the Z axis was moving as well and the distance between the Head and the bed was huge (around 1cm or half inch). And when I move it to the front again the distance reduces to be exactly the height of the card I was using.

At the moment I had an idea: let to turn of the printer and force manual the Head to move over the bed. Then I noticed that when I move the Head to back of the bed I noticed that distance was in fact increasing, but not too much as moving it with the printer turned ON. So I realized that for some reason the lead screw had lost some steps.

The solution: I opened the back of the printer, loosed the screw with springs that connect the belt from back lead screw to frontal lead screws (those left and right lead screws) and move it until the bed get aligned.

After doing that I tried to print again and the bed calibration worked:

Mesh X,Y: 10,10
Search Height: 5
Mesh Offsets: X=0.0000, Y=0.0000
Mesh Average: 0.07
Mesh Range: min=-0.7953 max=1.0249
Interpolation Algorithm: lagrange
Measured points:
1.024857 0.958892 0.898610 0.842575 0.789353 0.737509 0.685607 0.632211 0.575887 0.515200
0.858428 0.814137 0.759861 0.698626 0.633459 0.567383 0.503425 0.444611 0.393965 0.354514
0.693278 0.657536 0.606411 0.544454 0.476214 0.406243 0.339092 0.279311 0.231452 0.200064
0.529169 0.492602 0.442687 0.383368 0.318588 0.252291 0.188419 0.130917 0.083727 0.050794
0.365866 0.322844 0.273113 0.218679 0.161548 0.103725 0.047218 -0.005968 -0.053828 -0.094354
0.203132 0.151773 0.102114 0.053697 0.006061 -0.041251 -0.088698 -0.136740 -0.185834 -0.236439
0.040732 -0.017099 -0.065883 -0.108268 -0.146904 -0.184438 -0.223518 -0.266793 -0.316910 -0.376518
-0.121572 -0.180261 -0.226453 -0.263906 -0.296380 -0.327635 -0.361430 -0.401524 -0.451677 -0.515650
-0.284014 -0.334204 -0.375171 -0.409906 -0.441399 -0.472640 -0.506620 -0.546328 -0.594755 -0.654891
-0.446831 -0.475415 -0.507612 -0.542959 -0.580994 -0.621254 -0.663277 -0.706601 -0.750762 -0.795300
5:05 PM
Mesh Leveling Probed Z positions:
-0.446831 -0.542959 -0.663277 -0.795300
0.040732 -0.108268 -0.223518 -0.376518
0.529169 0.383368 0.188419 0.050794
1.024857 0.842575 0.685607 0.515200

Update: reading again the comment from the user from Youtube, I think what I did is similar what he did, but I adjusted the back lead screw instead of adjusting the two lead screws from the front