Lines on one side of prints

[mrjo118]

Hi,

I recently bought my first 3D printer, an EasyThreed X1, which I've had for about a month and a half. It was doing ok initially and then I modded the printer last week to add a part cooling fan. Since then I started having an issue where every print consistantly has visible lines (usually around similarly placed layers) on one side of my prints (always the same side). I have been using the same spool of filament (PLA) and tried relevelling the bed and that didn't make a difference. I have attached photos of a calibration cube, showing the issue. The lines are on the Y axis face, but only on the side which doesn't have the Y printed on it. Any ideas what might be causing this issue?

https://drive.google.com/open?id=1Uf...VlUjLcCUnT6jBx

Regards

Josh