Thanks again.
What really annoys me: I have now looked at the assembly instructions for the SMV46KX03E/28 on the internet (see attachment). It is clearly shown under No. 15 that 6 screws (the upper ones are missing in my case) and also two front mounting hooks at the very bottom should have been installed (see green arrows). So it's no wonder to me that something broke off there. The problem is that it seems the user manual served as a kind of template for all the drill holes on the furniture front. You have to place it large-scale inside on the inner side of the furniture front and then mark the later drill holes through the pre-punched holes in the instructions. But now, later, without the user manual, it is quite difficult to locate the correct holes, especially for the mounting hooks at the bottom..