Hi, As an FYI the wiring chart for the three speed hunter fan (at least for the Vista model) is as follows:
Green - 3
Grey - 1
Brown - 2
Black - L
These switches are proprietary to Hunter and if you need a replacement you will likely not find it in your local Home Depot. You can however contact customer service from Hunter and they will ship you out a replacement in a couple days. Other switches will give you a couple settings but not all of them and if you wire them wrong you can just cause a short / electrical problem.