Hey, I had the same exact problem. How did I fix it?
I took it apart, piece by piece. I'm sure you can find a tutorial on here how to do it
Then, unscrewed the analog stick from the motherboard. Took off the bottom metal plate, and found that the runners were out of their tracks. I took them off one by one, and then carefully replaced them inside there with a pair of tweezers, making sure that they were all in the tracks. After, put the bottom metal back on, and put it all back together, and worked like a charm ever since.
P.s., mine was bought in the U.S. and I live in Europe too, so same problem as you
Hope this helped!
Jotek