somewhere around 2016 without making a fuss about it. I had the same question and even contacted the manufacture in Glashütte. The gist of it is that the preloading has been done away with but the movement has the same reference and there is no way to see which variant of the movement the watch hous
Here's what it looks like when carefully taken apart. Warning! Do not attempt to do it at home! It may incur a serious injury to your nervous system if you drop one of those f..ing gold screws on the floor!