Lines along Z-Axis on every print

Hi guys I have a Cetus 3D mk II (Extended) and I am getting lines along (some of) the z-axis when I print. What is causing these - I know Jason NG in the facebook forum indicated something about rail size but the indcation was this wouldn't be happening on the larger or the mk II printers - yet it appears not to be fixed. Anthing I can do about this ? - it's not something I'd want to live with.


Allright - quick update - this seems to happen (or be more noticable) with straight faces and the concensus seems to be it's the z-seam. Without g-code preview it's hard to see what the nozzle is actually doing. I printed a benchy and it turned out pretty ok. 

High on my wishlist for the cetus studio is g-code preview =).