how can I join lnb support arms of Gilbertiny 150

I do have a problem joining back support and lnb support arm of gilbertiny 150
the problem Is that to place joining plate where the holes are I must lift up another 4 mm but there Is no place to do that because lnb support arm Is already touching dish
what cause problem - Is It back plate rotated over vertical axis or back / lnb support arm Is bended
dish Is not new