This old reverse painted glass electric sign needed new lamps and wiring. I tried replacing the original 2 standard lamp sockets, but I couldn't find any bulbs that would evenly light the glass ad panel. The 2 bulbs delivered 2 bright spots and unevenly lit the rest.
I got some LED strip lights that are intended to be used under kitchen cabinets. They are only a quarter inch wide and a foot long. The strips can be plugged into each other for a long unit or a pigtail wire can be used between strips for flexibility in placement.
I put two 1 foot strips together on the upper part of the can and 2 on the lower with a pigtail jumper wire between. They are powered by a 12v transformer that plugs directly into the wall.
The new setup delivered near perfect illumination across the whole ad panel. The LEDs use less than 5 watts and do not get warm.
The end result after assembly is a glow similar to neon but not as bright. Nu-Enamel made auto finishes before WWII. "No Brush Marks"
I felt uncomfortable at first with modifying the original wiring and lamps with modern non-original alternatives. But it looked so much better than the original lighting, I got over it.
After I'm dead, the next owner can easily put it back to original.