I have a 2007 Avalanche C4. The wrap around seat back in front of the ski lockers and the engine compartment has a hole. Wanted to remove the back rest to get it reupholstered. Removed all the screws from inside the lockers and detached the hose clamps for the ballast pump. Seat still won't move. Can't find any fasteners on the left or right wrap around portions of the seat. Anyone know of any additional screws or attachments I might be missing? Thanks