Normally when a heater goes bad on a fog machine or a Circuit board It is better off to replace the whole thing!, if it is over a few years old. When fog machines get older their circuits tend to corrode due to the wet atmosphere they create. This leads to problems in the future. I have delt with situations like this in the movie industry and it is better to replace the whole thing. especially Chauvet's..... They are like the ford of fog machines. Le maitre's fog machines are great but they break down and get expensive to fix! Le maitres are mainly used for theater. Except for there lsg or lsx, we use those alot in the movie industry along with the High End f-100. You should thing about buying a High End Systems F-100, they are the way to go. They last many many years, even if they are used every day.
Hope this helps,