Thanks to Steve Mck for contributing to this FAQ!
Rear window switch cleaning If your interior rear door window control switches stop working then you can try to clean them. If the contacts are worn out then they will need to be replaced. The switches may stop working in one direction or both. They are just switches and can be cleaned to make them work again. You can confirm the switch fault by swapping a working switch from one door for a faulty switch in another door.
Do not remove the door lining. Pull the switch out of the door by the surround. The connector is a tight fit through the hole. Push the tabs on the connector to release the switch from the connector. Pry the back off the switch. It is held by small clips on all four sides. Next you have to pull the front rocker button thing off the switch. It is clipped to the mechanism and pulls out towards the passenger. This is not easy, but remember the switch doesn't work at the moment anyway. Once the front part is removed, you can pull the back out of the switch unit.
Inside you will find rocker switches and small contacts just like in the center console switches. Clean the black off the contacts and reassemble. Clip it all back together and plug it in again.
Pricing for INTERIOR SWITCHES (switches)