here the original message from bambulab:
For the external wall quality, we recommend increasing the nozzle temperature to 230 degrees.
You can also follow this procedure, to fine-tune the flow rate: Manual Flow Rate Tuning for better looking prints | Bambu Lab Wiki
I’m experiencing this issue on my 3 weeks old X1C. I compared my early-stage prints with the current ones, the layer lines just got worse and more obvious. (only printed with Bambu PLA basic&matt with a minor tweak to default profile settings) The support suspects that it’s the nozzle wear, (although I have no idea how a nozzle can wear that much within 3 weeks), my print time is 50-60 hrs in total for your reference.
Then the concern that haunted me since I first got the machine came to my mind. Remember how Bambu describes that there is a special wiping area on the build plate with a special coating on it, and the machine will repeatedly rub the nozzle at this area to get rid of the residual material.
Although they guarantee that it won’t affect nozzle life, I’ve seen the coating worn so quickly after a few prints as the machine does this wiping procedure for each print. After that when the machine runs this wiping procedure, the nozzle just rubs against the raw material of the build plate which is metal and makes weird noise.
In a nutshell, my point of view is this procedure explains why the print quality decreases gradually, the more you print, the worse quality it gets and this definitely needs to be removed for future software updates cuz it damages the nozzle tip and heat bed potentially as I’ve seen the nozzle dragged the wiping area of the build plate up and down during the wiping procedure and made the build plate warping.
Just some thoughts sharing since I’ve rarely seen people brought this up, this could be another critical issue to look at. Haven’t swapped the nozzle to justify my thoughts as most of you have done it and it didn’t help.
here is the video showing how the nozzle rubs the “special wiping area” of the build plate
I’m experimenting with Precise Wall in SoftFever, I have the feeling I see some improvement. 
Hello,
adjusting flow and advance pressure with BambuFever ( Calibration · SoftFever/BambuStudio-SoftFever Wiki · GitHub ) give me complete new set of values. I will try now this settings in Bambulab Studio.
Out of ignorance, i was putting my build plates on turned 90 degrees counter clockwise. I realized this was “wrong” and started putting it on with the nozzle wipe tab in the back as its designed. Now a couple weeks into using it like that, my p1p has developed this issue. I think youre 100% correct and they need to do away with this pre print gcode. Im going to try to find the exact gcode to remove for it and i will let you know if it stops this issue. Luckily i have a brand new nozzle to swap out.
Hello everyone, 
I’m glad to see I’m not the only one facing this issue. It’s been a month of trying various fixes to no avail 
, so I wanted to share photos of the current defect I’m experiencing with my P1S. Initially, the printer worked flawlessly, but it started showing this defect after some time.
My brother, who purchased a P1S around the same time, hasn’t encountered any issues with his prints. I’ve consistently used the printer in the same way since I got it, sticking to the default settings without making any adjustments. If anyone has discovered a solution, I would be thrilled to try it out. Thank you for your help.
These are pictures I sent to the Bambu support. ( No real response yet, no improvement yet )
I still have these quirks and they annoy me. I’m curious to see what support has to say about this.
Im also curious what the support has to say. I have similar issues and irritating sounds on the x/y axis when it moves in the rightsided front section of the bed. P1S bought in Dezember here.
The Front:
The Back:
A week ago it printed all good, but suddenly has this problems.
Are you still having this problem?
Yes, waiting for a new puley now, Not sur this will solve the issu but I have to try.
I started having similar issues and then the filament stopped feeding. Turned out the extruder gears were worn and the bad layers were due to the gear slipping. You might want to take the extruder apart, clean it and inspect the gears for wear.
Changed the pulley.
Disassembled the hotend and the extruder gear to check.
Tried with dried PLA, both basic and matte.
Adjusted print temperatures from 190 to 240 degrees.
I also tried with PETG.
No improvement.
Still working on it; every day is spent testing.
Please don’t spam the same message in multiple threads as detailed in the Forum Guidelines
Start your own thread and keep messages about the topic/issue contained to it.
I have the vertical ones. After the last firmware update. No amount of calibration has fixed it. I only have my old prints to prove the printer once printed perfectly.
Hello Jon,
Sorry I tought it was a good idea because it was about the same issue.
You are right I should open a new thread.
I had theme before the Update since day one ( november 2023). However there is nothing when I use vase mode. So I think the issu is not coming from the axes or the belts.
has your nozzle been scraping along your print? or bed? check if the hot end is loose. even if you know its not moving, check just encase.
