[Closed] Serrated caliper washer OK for carbon?

Had a bit of a disaster when removing the mud guards from my road bike - front caliper break did a mini explosion in the garden, and possibly lost a bit.

Issue is I can't get the brake to stay centered, and can't tighten the backing bolt down enough - it feels like maybe a washer is missing, for spacing and for tightening down. This is Ultegra 6770 - although from what I can tell the rear brake does not have a serrated washer either.

So question is - is a serrated washer OK/needed for carbon forks? I'm assuming it's definitely not OK, but no idea.