I cut a small hole in the corner of the door near the actuator (slightly bigger than my hand) so I could reach in and check the connections, then I figured out the things were just rusty and not wanting to move, but you need small hands and paitence plus a flashlight and mirror help.
What year is your truck? The '96 actuators are really expensive for the rear cc doors and it's cheaper to switch to the '97 style or try to fix yours. Sorry I can't be more help just passin along what I've learned.