Steam Uninstall & re-install question:

[Blitzen]

Recently my "aiming help "for bombing stopped appearing inside the aircraft ( the aiming circle still is visible outside views of the aircraft.)I've done a Steam verification of th files but that didn't work,so now I'm thinking of doing a complete uninstall & re-install,As I recall this isn't very difficult but I do wonder if I should copy or rename the folders that contain missions , campaigns, career histories,skins,mods  etc.? I cannot remember if the re-install doesn't interfere or replace all these with the previous ones..does anyone know for sure?