I'm nowhere near BC. In Florida actually.
It really is easy. You don't need to disassemble anything except the drum.
The first thing you do is remove the furling line from the drum. Tie a stopper knot in the line so that you can tell later how much line to wind up again. Remember to note which side of the drum the line is coming off of. Then remove the furler from the the boat by easing the backstay(s). Pulling the bottom pin and then going aloft, tying a extra halyard to the foil and lowering it. Try not to let the foils sag too much as you are lowering it.
Okay now you have the furler laying on the dock. Before you do anything, take a pin to pin measurement from the eye on top to the toggle under the drum. Write it down.
Now loosen the screws in the torque tube and slide it up to expose the lower terminal of the wire. If it is a mechanical fitting then the locking collar should have been backed up against the bottom of it. If it is a swage the the locking collar should be tightened down. Either way, loosen the locking collar and unscrew the entire drum from the stud. (Remember, the entire Harken drum is a turnbuckle. So you will probably want to loosen the star washer and back out the t-bolt on the bottom of the drum so that you can start the top and bottom threads evenly.)
Now all you are dealing with is the foil. The best way to replace the wire is to have a new one made up a foot or so longer than you need with a swage eye already attached to one end and the other end obviously open.
Cut a terminal off of the old wire. I usually pull the wire out from the top, but it doesn't really matter.
Now, with the open end of the new wire filed or ground into a smooth rounded tip, start feeding it into the top. You will soon hit the first connector. At that point, while holding holding the pressure on the wire against the connector, rotate the entire foil assembly in the direction of the lay of the wire
and it will find the center of the connector and pass through. Repeat the process at each connector and soon the wire will be poking out of the bottom.
Then you just need to figure out where to cut the wire to install the lower terminal (stud).
I would recommend that you use a mechanical fitting for the lower terminal. It's a lot easier that carrying a thirty or forty foot piece of extrusion to the swageing machine.
Then put everything back together and put it back up.
Feel free to call me if you think I can help. PM me for the number.