Wavy prints with a brandnew k1max

Hi,
After 5 or 6 beautiful print’s all my prints end up like wavy on all walls. I checked all the tensions, nothing abnormal. I use creality hyper pla, creality V6 slicer.
3 friends of mine have also the same K1Max machines and they print the g-code’s that I gave to them as it should be. Very frustrating!
I contacted the technical service but no answer yet.

Nobody there who can help?