Strange Y axis beahviour

Hello there

I have a bodor 1309 based laser, working fine for 4 years

Last couple weeks it started to like loose som mm betwwen layers.

After some time cutting is like the material is beeing pushed up in the table. It starts to come closer to the bottom far side of the bed.

This is a 3 layer square.

If i cut by layer orders several squares,the layers start com come together at the bottom:

The layers were cutted outside first, then inside, then middle layer.

If i cut from bottom down, grouping by object instead of layers, small objects, it is not very bad.
Here is the point where it started the cut and below where it ended.

But with big objects it is impossible.

Already changed motor of the axis, checked all connections to powersource and controller, cleaned and lubbed all guides, bearing, rails… Checked belts… Same thing on LightBurn and RdWorks…

Have no more ideas what could be causing this.

Anyone has had a similiar issue or has any idea how to solve it??
Thanks in advance.

Best regards
Eduardo Sequeira