horizontal lines in my prints

[Ailos81]

Hello,

I need some help, I could print a correct figure yesterday but with the example today I found a weird horizontal lines. I was searching I'm foros but I didn't find any clear answer 

Please, can you help me?

[JohnPH]

I am having the same problem today. When I find out what it is , I can let you know. Unless you already figured it out?

[cliffyk]

The Z-axis trolley needs lubrication and/or adjustment--Youtube video: this fellow calls it "calibration" but it isn't...