Hmm, what type of camper? If it is Coleman, be careful with lube on the chain. It can be bad for the part that holds the roof up.... http://www.campersolutions.com/home/help-my-roof-won-t-lower
You can remove the screws and drill any rivets out then cut the tape under the top rail to remove the back panel. Sometimes you can just remove the lower screws, spare tire and bolts (they just screw out) and bumper. This can let you pull the bottom of the back out enough to access the chain. Just don't lube it up and get the brake messed up. I don't suggest any lube, but that's just me. Maybe clean the chain.
