I had the same problem but i found a quick fix that should cost you about $20 and a little bit of time.
Go buy yourself some electrical contact cleaner in a spray can, any hardware store, car shop (repco autobarn) or even jaycar show have this.
Remove the master switch unit from the door disconnect any wires.
Spray it with the contact cleaner while flicking the switches, dont worry its non conductive and it will evaporate so it wont short any circuits in the circuit board
It should clean off any lithium based greased which is clogging up the switch.
Listen for the clicking noises when u flick the switch this means its working. Let it dry off and reinstall.
