Hey Tom,
I posted on your UK WIP earlier today but just for clarification here, the Sniper pad needs to be lowered such that the two extreme corners of the hexagon is in alignment with the sloping edge of the shin armour behind it. This is based on the two attached screen grab images from the original 1977 movie. I've also added a rough hand sketch of the alignment as it would look if viewed from the front face of the sniper pad. The red ink lines is where it should be aligned to while the black ink lines is where you currently have it positioned. Hope this helps.