I just bought an Ultimaker 2 and it has started making clicking sounds.
To me it sounds like a wood click, or structure shift, its either happening in the back left corner (on the short belt and the motor) or on the rods (left and right ones).
I still have those "click" sounds when I move the print head manually. I can't see anything hitting the sliding blocks or directly hitting the corners.
It looks like clicks only happen in y axis. And it only happens in specific places.
I tried re-alligning belts but either I did it wrong or the belts aren't causing the problem.
Also I tried moving the left rear motor a bit up to lower the tension on the short belt.
It looks like it doesn't affect the print quality (much).
When I changed the positions of the belts (also the motor and the short belt) frequency of the sounds changed ( the tone and volume of the sounds didn't change).
Sorry for bad English.
Thanks for the help.