Y-axis isn't level
I'm having some issues with first-layer calibration: close to the bottom of the mini sheet where the test starts, I can calibrate the z-axis to print correctly, but as it moves back to where it makes the filled in rectangle, the bead starts to lift off of the print bed. Calibrating the z-axis lower throughout to get a good print of the rectangle makes the print head strike the print surface at the beginning of the test.
I tried printing the bed level calibration model, and have included a picture of the results, it seems like something is definitely off. I tried searching through the forum and knowledge base, but couldn't find anything documenting this specific problem, so any pointers would be very much appreciated!
RE: Y-axis isn't level
Another wrinkle that I forgot to mention last night is that the z-axis will regularly fail the self test, but not reliably. I can run it four times, and it will pass on the fourth. Sometimes it fails immediately, but others it will make it 3/4 of the way up the z-axis before stopping and reporting a failure.
Things I've tried:
* Debugging the Super PINDA according to https://www.help.prusa3d.com/en/article/m-i-n-d-a-superpinda-sensor-testing-mini-mini_134021 - I wasn't able to find any problems based on this article
* Opening up the case and checking the z-axis and SuperPINDA connections - nothing was loose and everything seemed OK.
* Re-calibrating the height of the SuperPINDA probe as specified in the end of the build instructions - this caused the self-check to pass, but trying it again this morning the self-test is back to failing on the z-axis.
Additionally, after trying a few first layer calibrations with a successful self-test last night, the printer at one point drove the print head into the build platform, melting the plastic surface of the steel plate. I hadn't set the z-axis adjustment to a distance that would cause that, which makes me think that there's something wrong with the SuperPINDA.
RE: Y-axis isn't level
For some additional context, here's a video of the z-axis self test failing: https://photos.app.goo.gl/1jsCoPuqXxQCHMNh6
RE: Y-axis isn't level
Loosening the screws that hold the x-axis to the z-axis rod helped a little bit (this thread seemed to be very similar to what I was seeing: https://forum.prusa3d.com/forum/assembly-and-first-prints-troubleshooting/mini-kit-z-axis-fails-self-test/#post-382240), but now the z-axis self-test fails near the top of the axis. Manually moving it up at that point yields some pretty gross sounds: https://photos.app.goo.gl/CYpCjULhjxtGeVy56
RE: Y-axis isn't level
I have no idea why this worked, but downgrading the firmware to version 4.2.1 caused the self-test to pass on the first try, first-layer calibration to work without issues, and yielded great prints afterwords.
RE: Y-axis isn't level
Well I spoke too soon -- I tried to start up a print over lunch and the self-test is failing again. I have no idea how it can go from producing perfect looking prints to failing the self test overnight.