However, damage was evident inside the rear light which no longer worked. The previous owner has used silicon sealer to stick a battery operated light on top f the original. A fix was required.
The light unit had seriously corroded terminals in both the harness plug, light unit and the switch. I only operate the light via the door mechanism so decided to identify the correct feeds from the three cables and soldered new wires to the light terminals and by passed the plug and switch.
The rusty stains were tackled next. The plastic lens is frosted (helpful) so I attacked it carefully with a brass wire brush. Job done. Pleased with the cost free fix
