Happens on a part with a large solid flat surface area on the bottom and a large flat place on the top.
Does this indicate a fan that is under-performing (they both work with fan test) or could it be something else?
Could be also PCB / Heater / Ribbon or underperforming ext FAN(s).
Gather few photos and give us a shout through www.support.zortrax.com/support-form
Hi Marcin, cheers.
What exactly do you need photos of?
I just bought the printer second hand, it had very recently been serviced by Zortrax so it's a bummer it still has problems.
Try printing [url=http://library.zortrax.com/project/ribbon-cable-tester/]THAT[/url], make few photos in case of any problems and attach it to Form given above