Movement of the X or Y axis causes movement of the other axis.  

Movement of the X or Y axis causes movement of the other axis.

After converting my MK4S to Core One, I had very good printing results until two days ago. From one print to the next, my Core One is no longer usable. First, I noticed that the purge line is no longer in the front right corner. Instead, it is offset diagonally to the left rear, about 1/4 of the way inside the sheet metal. The print then also starts too far back on the left.

When I move X or Y manually, I see that when Y moves to the stop, the extruder shifts a little in X and vice versa. I have now moved the axes by hand with the motors switched off. I noticed that the Y-axis is sticky in several places. There is a clearly noticeable resistance. I am not sure whether this is coming from the motors or the shaft/bearings. After a few movements, however, this disappeared and it is moving normally again.

However, the next print failed again.

It seems to me that this could be a common problem with Core-XY, but I don't know the term for it. Let alone the cause... I also can't remember reading anything about it here in the forum.

I would be very grateful to know where this behavior comes from and how to stop it.

Thank you very much!

Stefan