I had this happen with mine, the way the switch is built the fog light feature is run by two metal tabs that stick out from the back of the knob shaft, You pull out on the shaft and this brings them up to contact and the lights come on, over time these tabs bend and no longer sit flush against the contacts. If you take the switch out you can take it apart but be careful, as there are some pieces that will fall out and you need to know where they go. Once you get the back of the switch assembly you will see right away what I am talking about, then just carefully bend those tabs down towards the contacts not very much just enough so that they will hold tension. I personally felt that they would just return back out over time so I took the time to reinforce it with a second piece of metal and just soldered them together. Little bit more heavy duty and when I checked it with the meter showed no change in resistance so it should not affect the current flow. Been two years now and still works fine. All in all it took me about forty five mnutes with the soldering and everything. You should be able to do it quicker than that, as you will know what to look for. I was flying blind when I did it. Good Luck
Jon