1. Check whether there is already a thread on the content in question or whether the content appears in the list of important add-ons.
2. Enter the exact paths of the missing objects / splines / textures.
>Sceneryobjects\Chuckinhos Werkstatt\TEC\tecplaque.sco Sceneryobjects\The_Gamer_2015_Objects\TG15_Blinkerobjekt_left.sco Sceneryobjects\The_Gamer_2015_Objects\TG15_Blinkerobjekt_right.sco
3. For which map do you need the content?
>aachen-walheim