I read the post “Lopsided/Skewed Prints” by djproductdesign because I have the same kind of problem.
So again I tightened every screw I could find and checked that the short belts aren't rubbing on the frame, just like Illuminarti and gr5 suggested.
But without any possitive results.
The problem appeared all of a sudden and first look to have been gone but now it's even worse.
The firts models where perfect.
– For the firsttime it's slightly visable at the Owls but I didn't took a note of that because after that I printed some blocks which where okay.
– Than the Mont Saint-Michel b