E-30+ mast wiring

I decided that as long as I had my mast I would replace the wiring inside the mast. (talk about making work for yourself) Because of the twists and turns the wire follows it is impossible to run any type of messenger as you pull the old wires.
Their is a wire raceway on the back side of the mast through wich all the wires pass. Their are covers over the wire race but I can't seem to figure out how it comes off.
Any help out their?

not sure what mast or vintage, but the kenyon spar on our '88 E-38 had the cover slide down to the bottom after removing a couple of screws.
Chris