Calibration failing with varying messages  

Calibration failing with varying messages

I just got my Mk3 this week as my first 3D printer, ever. I ran through the initial wizard and, with the exception of having to tighten up the X belt, everything appeared to be fine.

I made two of the test prints, seemed to go OK.

I move on to try to print something besides a test print, the printer goes haywire. The extruder moves to the far right and is spitting out filament like crazy. I hit reset.

I try again, the extruder started to pickup my print and move it all around the bed. Ok, so I go back and adjust Z. Try again, looks good starting out. Nope, calibration error. Ok, so I go through the wizard, again.

Looks good, all checks pass, calibration is done. Start the print again, many layers in (like 2-3 hours), it decides the bed is not level (isn't that a test performed at the very beginning of each print??). Ok, so the extruder is now front center. I try the bed leveling calibration. It must think that front center is front left because it ultimately goes extreme right and grinds.

Ok, let's move X back to a rough approximation of its starting location in the menu. Nope, can't do that, it already thinks its at center. Hmmm, OK. Let's do the calibration again. Fails with the same error, bed isn't level. I get some really weird output on the LCD screen, a bunch of characters that don't make up English words nor Czech words near as I can tell. Ok, this looks like possible firmware corruption. Redownload, reflash firmware. Go through the wizard. Almost everything checks out, it says XY is slightly skewed.

Ok, for good measure, let's try a different print. Now it fails telling me to check the X axis length. No idea how to do that, the manual doesn't say, so I start Googling.

Apparently the #1 cause of this problem is a cable hitting either the left or right side and causing the unit to think that's the furthest extreme it can move. This was a pre-assembled unit so that's kind of strange. Ok, I'll check all the cables, not seeing anything that is hitting the sides. I checked the top, etc. Not seeing anything. Ok, maybe it was a one-off. Let's do calibration again. Oh wait, can't do that, the extruder is front center again and thinks that's front left, let's go far right and grind away.

Fix that, start calibration again, same error. Wiped out the calibration config and started wizard again. Same error. Reflash firmware again, run the wizard again, same error. When doing the very first calibration the X belt was too loose and that threw an error, well maybe I overtightened it, I'll loosen it up. Same error. Ok, let's try and tune it with a known working belt, the Y belt. About the same tension, same error. Now I'm at a point where somehow X and Z are so far out of whack that when running calibration, the head moves down so low that the bed is bending. When this occurs, I think the extruder head is so far to the right that it's off the bed so at least the bed isn't being damaged. I usually panic and hit the power switch at this point so the bed doesn't get damaged

When the extruder is in the wrong position and has to be corrected, how does one do that? Physically move it or is there some sort of hidden way to do it in the menu? I would think the first step of every print or at least calibration should be to move as far left & forward as it can but it seems to think it's in the right place.

What do I do now? I'm not seeing any indication on here that the firmware version is bad. Maybe I have a bad unit. Maybe I'm just too new to the whole thing and I don't understand what these messages mean, user error.

I tried emailing Prusa but haven't gotten a response and I'd really like to use my printer.