Uneven y axis

My printer has printed fine for about a week but a few days ago, the print layers started becomming a bit uneven. When it first started, we could hear a clicking noise as the printer moved on the y axis. If I manually move the printhead on the y axis, the resistance is uneven, in some places it takes a lot of force to push it an in some it takes less. I had a similar issue when I first got it working, the y axis moved really unevenly and on the second print, it stopped completley because the motor didn’t pull it with enough force. I lubricated the 3 y axis rods with sowing machine oil. I have tried doing the same thing again but the prints still turn out a bit uneven.

I tried printing some cubes and they all turned out with the same problem. All 3 of them were printed in the center of the printer and the side facing the front looks great. The first few layers of the back look just as good but as the print gets higher the problems start appearing more. Here is an imgur album showing the issue http://imgur.com/a/KFON4

What could be causing this, the x axis is almost flawless and the y axis is a lot worse. I did touch the rods by accident quite a few times when building it but I assume that wouldn’t cause an issue like this after just a few weeks, especially not since the y axis is so much worse and has always been uneeven

Edit: Fixed image link

G’day Z

Check that the pulley is tight on the motor shaft. If you can see the end of the shaft, mark it and the pulley with a thin line across both. You’ll easily see if the shaft moves relative to the pulley. You may need to tighten the set screw.

On my machine, I noticed yesterday that one of the pulleys runs eccentric and needs to be swapped for one that runs true. I’m waiting for the supplier to reply. This is something worth checking as it affects the accuracy of the travel rate.

Good idea, I have had some issues with loose pulleys. I’ll have a look tomorrow

EDIT: I re-tightened the pulleys which made the movement smoother but it didn’t fix the quality issue.