Strange diagonal artefacts on perimeter on A1

Hello to everyone,

I have few issues with my A1 bought in november. I’m in 3D printing since 2015. I have 2 other printers at home and a A1 Mini at my job.
On the A1 Mini the quality is really better than on my A1, better layers, no artefacts. The only common issue is bed adhesion. My only way to resolve bed adhesion was to move the z-offset and add 3dlac on a smooth plate.

I really need some help for the print quality.
For this issue, I give you some pics of diagonal artefacts that appears on one side of this little cube just before the seam.
I have checked the g-code and there is just less flow on this side compared to the 3 others sides. On the A1 mini with the same settings, the peremiter are perfects.
If you have an idea of what can do that, I think there is an issue with the extruder. You can also see that the surface isn’t very good with some banding.




The second issue is the dimensional accuracy, I have printed tons of cross calibration to get it accurte but the A1 has always a constant error between -0.1 mm and +0.1mm. It is not shrinkage but random error.

Thank in advance.

Tram your bed. That looks like mesh warping.

I have already trammed by bed few times. It is perfectly aligned but the bed isn’t perfectly flat : 0.2 mm lower in center than corners.
And these artefacts ony appears on one side of the cube on y axis.
I can’t do nothing more for my bed.