K 8400-Print moved slightly to the left every few layers!

I have a new problem while printing PLA. The x axis parameters varies every few layers so the print is uneven and ugly (bent to the side) Is it the loose pulleys problem?? It seems like the print head rapidly moves to much to the side along the x axis. Any suggestions? Thx

Hi. I’m very new to this machine, however I did see something similar on YouTube. I beleive the answer was to lubricate the slides. It seems that there was some binding, causing the print to slip slightly - something the controller can not compensate for. A little grease solved the problem.