There's a procedure in Pelican's how-to section for the 986. It's near identical.
As I've been dealing with the same on an '06, make sure you check the roof gearboxes for looseness in the arm. On the 987 in question the pushrod end on the right snapped, and even with a replacement and alignment it jammed shut. Turned out the input cog on the left gearbox had decided to break-up with its output shaft.
