A day ago my printer started to act weird. Bed seems warped & some layer of Z-axis has weird lines.
Tried to do all of this in a video of maintaining the printer. It didn’t solve the issue. What else am I able to do ?
I bought it 2-3 months ago.
I use generic PLA with 0.20mm Standard BBL X1C,
I clean bed with soap and hot water before every print.
Looks like there is some warping on the base.
Clean the plate: water and soap, rinse and dry lightly with papel. Then left it dry completely and try printing.
I do that before every print
I watched the video you linked above. He did a good job of hitting some important cleaning and applying grease.
But he missed cleaning all three lead screws. The lead screws need to be cleaned very well also. He also really didn’t use enough IPA to properly clean the carbon rods.
He also didnt retension the belts. I think this where your banding on your prints is coming from.
Here is a link for maintenance with a lot of cleaning tips that are highlighted.
An interesting one.
Firstly, regarding other posts, cleaning Z axis lead screws and tensioning belts and such obviously have nothing to do with this — certainly not cleaning carbon rods. These printers are not made out of cotton wool. That said …
From the first two images, I might also conclude that the bed plate is wonky but not in a way that merely “washing with soap and water” is ever going to fix.
One thing that can occur after removing the plate and reinstalling is a small piece of plastic from the print laying on the magnetic sheet, which then get sandwiched between the mag and built plates. If it was PLA, it can end up “baked onto” the underside of the build plate. You would need to scrape that off, since a little soft rubbing with soapy water isn’t going to budge it. If it’s a similar color to the bed, you may not even be able to see it without looking carefully. Perhaps run your hand over the surface.
It’s easy enough to miss something like this. We remove the plate, inspect the magnet sheet and see nothing. It doesn’t always occur to one to check the underside of the plate.
Having said all that, it’s practically impossible to imagine such a thing could cause such a “dent” over such a small area. Is it possible the plate got dropped and dented or something? Perhaps by someone with smaller fingers lurking about the house? (Obviously I’m stretching here. Trying to think outside the printer’s enclosure, as it were.)
I cannot imagine any other mechanical issue that could cause the print defects shown in your photos. Certainly NOT belts, lube or any need to clean lead screws with IPA — especially not after just three months of use. Either way, nothing in the print sample photos bear any evidence for any of that stuff.
Another possibility comes to mind. I assumed you must have already run your hand over the magnetic build platform surface to feel for bumps. I also concluded in my head that such a bump surely couldn’t translate to such a pronounced, isolated change of shape in an otherwise large, spring steel sheet.
That said, if you do happen to find a defect in the build platform — or if you cannot figure it out at all for that matter — do not hesitate to raise a support ticket or even live chat with BambuLab. You may never have experienced the amazing level of support and willingness to simply send out entire new build plates with installation instructions to us mere end-users. BambuLab are not like any other Chinese company you’ve ever dealt with before, except maybe DJI. Their practical attitude towards getting people going again without the usual “ship the whole thing back for service” nonsense we are used to is almost astonishing. Give them a go! 
Thank you all @gruvin @Barryg41 @ElektroQuark for your suggestions. Gave some insight that I didn’t think of. Will try them later today. What I’ve also tried yesterday which partially( prints now look WAY better without any warping, but still got some less seen Z-linesn) solve the issue. I did auto calibration(the one, which takes up to 30minutes to printer self test itself).
