Passenger side reverse light faulty

[Thrill]

Some times it works, sometimes it doesn't. If I give the cluster a bang it seems to work. It's not the actual bulb as I've replaced that. What else could it be? I've cleaned up the connector on that side too. It's not the sensor as the other side works fine!

 

[Thrill]

Anyone got any ideas?

 

[Alan]

Water ingress, rusty connectors?