My airport would only work if the computer did not move after startup. If moved the airport would turn off and could not be turned back on without restarting. After researching the problem I deduced that it was probable that the antenna wires had been pinched/worn from the screen opening and closing for three years.
The repair took me quite a while, about 2-3 hours. I followed the installation guide to the letter and when completed my wireless works like it supposed to. I even shook the computer just to test it. The hardest part was step 20 putting the screw back into the cd drive. I used the spudger and a screwdriver with some patience to get it back in. Also, don't break/lose the small grey clips that hold the display bezel in place, as you will have no replacements.
The screws are hard to keep track of after removal. If you can, use some sort of divided tray for all the different sizes. Or use a metric tape measurer to figure it out like me.