53flatbed,
Dim 6v bulbs are usually a result of bad electrical grounding. Our 6v lights do not have a separate ground-wire, so the ground is often provided by the electrical continuity from the light housing/fixture/socket back to the frame (though bolts and screws). These "contacts" corrode/oxidize/rust over the years and provide a weak ground.
I have had success in having bright 6v bulbs after cleaning the screw and bolt holes back to bright metal and then
applying a conductive antioxidant "grease" - Kopr-Shield .
Tim
