Lucky it was not fully dark at the time, as all lights go out!!! - done that once before in the total dark & roo country

The plastic base that the metal contacts are riveted through goes soft, allowing the contact to retreat and not work any more, all lights go out!
Am running standard wattage globes, so they should be fine, driving lights are through a relay, powered from battery direct.
Was wondering is this a common failure?
What mods can be done to cure this problem?