Hi Thierry,
Did the dealer explain why is was locked? Had the same problem on my new roadster. Very hard on the front. Turned out that the bottom of the kingpins were covered in thick black undercoat. This made the front stick. Was OK after cleaning/greasing. When I mentioned it to the Dutch dealer he said another possibility is tight bushes. Aparantly the factory switched from reaming to honing the bushes? On some cars they are too tight and freeze. I also tried lower tire pressure but I find the car then "bobs" more on the tire. Problem with that is it is undampened so it easily turns in continuous nodding (when going slow) With the front suspension working good I find 1.8 gives a better ride. Cheers J