Cleft dimension

And then there's the next question:

I am disturbed by the gap between the headlamp and the lath (SCR headlamp cleaning system). The measure should be about 4-5mm evenly from the very left to the very right bottom of the SW.

Unfortunately, this is no longer the case since I took off the bumper once. Since then it is rather a "flash bow" where the gap to the middle gets bigger, and only at the end is true again. (see Annex)

Because of this fact, I've been working on it several times, but I can't handle it. Funny way, exactly the same thing happened to me on my second V8 .... After the removal of the headlights and the replacement of the SW rubber, I had the same crooked gap after the assembly.

Does anyone know advice or what I might do wrong again and again unconsciously?

Mfg