It's very simple to remove. Just pop it off by prying the horn button on one area gently with a screwdriver. It basically snaps on. There are three adjustment screws to move the brass coloured plate in or out . I hope you dont't have any trouble with the screws because I had some strip the threads in the column on me.
Hope you don't find what I did. The horn contact parts are copper as stated. A ring with a spring loaded wiper. On my GT the copper ring was worn through in the wheel straight position causing no contact. See if yours works if you turn the wheel from straight. If so, bet it's the same cause. Otherwise the previous posts give great tips!
Anybody out there know of a good fix for mine?
The wiper pin and copper ring can both be replaced. I think I have 5-10 of the copper rings, but the pins are a bit trickier. I know I have at least a couple of used ones, so I'll double check everything tommorrow when I get off the mid shift and let you know.