X and Y Axis change after Z movement

Sorry about the confusing title, I did a very simple test cut of a square and the letters “TL” inside. The cut started fin but with the third shape, in this case the letter “T” the bit came down in the wrong location changing the cut. See pictures for an example. Any thoughts on what could be causing this issue?


I had an issue like that cause by loose belts that slipped during the cut. Looks like that is what happened here, while the machine is running if you see the belt jumping in front of the smooth idlers then the belt might be too lose.

Good to know thanks!