someone probably cranked the cam bolts down too much in the past and closed the opening some. i usually hit them in with a hammer and block of wood.. may have to spread the openings a hair.
I agree. I just did this a month ago, and had one side that just wouldn't cooperate. I persuaded the opening up a little on both sides, used some grease and a BFH (rubber) to tap the control arm into place. It'll go...eventually.