Filament retracting cousing under feeding

Hello!
My name is Casper and i have bought your 3D printer k8400. It printed good for some time but now it has started acting out.
It has started retracting the filament randomly. It prints some layers perfect and it allways feeds filament in a slow and steady pace but once in a while the filament retracts about 0,5 - 1 cm and then continue to print. This resulting in a web-like structure on the print job. I have tried checking the voltage to the stepper driver, tried different slicer programs, updating the firmware, disableing retraction.

I’m running out of ideas and need help.

Regards, Casper Christiansen