Old & Slow

Just got a new OEM Benelli M1 Super 90 extension kit to allow the tube to hold 7 rounds ( currently holds 4 ) However the spring that it came with is 33 1/2" long !! Been trying to get the %$##*^*!! in all day and there is almost no way to get it in without kinking the coils, is the the correct spring to use ?? Can`t see how to get it compressed for 7 2 3/4 " shells in even if I do get it in. Any help appreciated !