If just one lever broke off the 3 lever switch, Did just the casting on the lever break? If so, it can be unscrewed and replaced. If you need a quick fix, take the 3rd one off the left for the panel/gauge lights. If the handle broke off with the screw and the plastic behind it, you will likely need a replacement 3 lever switch. 4 screws, and a couple on the levers and it will come out easily. The 3 lever switches are pretty common and almost universal to all mv's.
I recently upgraded to an electric led push button one and love it. It is so much better than the old clunky 3 lever and back lite for easy nighttime viewing.
Download and read the tm's as they will give you a world of info.