I have a 2-week-old Ultimaker2, which was printing well until it started showing some skew. Turns out that the X-shaft, which runs front-to-back along the right of the instrument was falling out of the bearing located at the front right. If I put it back in, it will eventually pop out again as the printhead moves around.
Looking at it more carefully, and after removing the motor cover, it looks like the short belt between the X-motor and this shaft are at an odd angle, with the pulleys too far forwards on the shaft. This could be pulling the shaft backwards and causing the problem. I cou