Unknown 'scarring' issue

[NicholasBunn 0]

Hi everyone, Im quite new to 3D printing and have run into an issue with my prints. I am not entirely sure what is happening so I'm struggling to search for help. Basically when I print a large, flat (floor-type) surface I get this zebra-stripe scarring on the top layer. It doesn't seem to happen on other type of prints so that isolates the issue a little bit.

 

It looks like either the plastic is melting weirdly or the tip is gouging the surface, see the attached pictures for a better image. Initial thoughts were overextrusion (which I've checked), bad bed levelling (which doesn't seem to be the problem as all other layers print perfectly and other prints have no problems), incorrect nozzle or bed temperatures (I'm not running them particularly hot though), and then finally, a top/bottom layer thickness that is greater than the thickness of the surface being printed and thus the layers are not completing.

 

I am printing on an Ender 3 Pro with PLA at 190C to a bed at 65/70C, slicing with Cura.

 

If anyone has any suggestions or thoughts, even if it's just some direction to look into please share them, they would be greatly appreciated.

 

Nic