A trick the Vdubbers in my club apply to their old VWs is WD40 in the sockets. The 6V systems are terrible regarding flickering or inoperative lights due to mild corrosion. So if you have to tear into all the sockets, etc. , might as well give them a little WD40 bath. Plus, the aroma is really great. (I'm full of shade tree ideas tonight)

WD-40 is an excellent choice for this. It'* NOT a lubricant. It'* a water-displacing solvent.

Get it? Water Displacing. WD. That'* what it was invented for.