We have these in our house, and I've concluded they are junk and designed by some engineers that should not deserve to have been graduated a construction hochschule. Some very elementary design mistakes ruin the experience. What is wrong? - You cannot remove a turning part of the window if the mechanism locks. Screws to remove it should be on the inner side you can access by removing the glass. - The hooks that are in the outer frame have to be inserted before making the frame, and thus it is impossible to move a turning element to another position. - They are tumble/turn, just turn would be much better, and it lacks an easy adjustment to fix the mech to just one operation. Also the tumble position comes first. Having turn as first position would be better. - Screws are very low quality and not all are true screws, some are like t-bars that unlock when turning 90 degrees. This is not clear, and it is very easy to damage - Companies for repair/maintanance are impossible to find and therefore those who exist crazy expensive. - You cannot split the frame and replace either the inside or the outside. Both are welded together by heating the plastic heat bridge. There should be a way to disassemble the sandwich.
