be able to repair your current fan switch by simply cleaning it with vinegar. Especially in older bikes that sit, or have sat sometimes for years, the switch can become gummed up and stuck.
The switch is actually three pieces and the end cap is removable.
Because this part sits in the coolant it attracts the same gunk that plugs your rad.
Easy step by step process - and I'll add pics below when I remember how to do it.
1. After the switch is removed from the bike it is best to soak it for a few hours in a straight vinegar bath. This helps break up any corrosion that has accumulated on the threads that hold the end cap.
2. Firmly grip the main body of the switch - I used a hand held pair of vice grips where the wrench would normally go.
3. DO NOT GRIP OR TURN THE END PROBE - WHICH IS THE COPPER PIECE ON THE END.
4. Underneath this end probe, there is a small and very short shaft and then a slightly larger piece. In profile there are eight distinct sections of the switch. You are looking for the third distinct piece counting the end probe as number one. (Shown better in the photos)
5. Grip this third section with a needle nose vice grip and turn it gently to unscrew it. It will take some effort but not much. If you are stripping metal off it like I did at first, it probably needs to soak longer.
6. Once the end piece is removed you will see a pin that is supposed to slide freely inside.
7. Soak the end piece with the pin in vinegar overnight and it should loosen enough to pull the pin out. If not, let it soak some more.
8. When the pin is removed, use your fingernail to scrape off any more residue that may be stuck on it and clean out the hole where it sits. I used a toothpick and vinegar bath.
9. Once clean, the pin should slide very easily in and out of the hole.
11. Test, or not, to suit but should probably test as this will only work if the switch is broken because the pin is stuck.
Hope the pics attached ok. If not I will add them again later.