Lets hope you got one of the 'good' AOS replacement units. Reports previously indicate even some OEM aos are doa !
The ideal tool for this job is remote pliers with a picatinny rail+ flashlight
Mayhew:
http://www.amazon.com/Mayhew-Select-45650-Clamp-Plier/dp/B0000AXA53
http://www.amazon.com/Mayhew-28630-Rigiflex-Clamp-Plier/dp/B000TRQOCM