My '37 Chevrolet has terrible dash lights, and as I get older they get harder to see. This how they work, two bulbs on each side, with a slot for light to pass through, the side gauge pods have the same slots. I have them painted white, new T1893 bulbs, voltage is good, no dimmer switch, grounds good. This one shown is a spare, they bolt flush to the back of the dash panel. The gauge faces set high in the housing letting even less light across the fronts. There were plastic lens across each slot when new. Glass is concave, not sure it matters though. Face decals are light tan, dark brown lettering. Here is how they look in the dark. I don't worry about the tach, it's a cheap-o with crappy lights. I'm thinking maybe an LED strip around the inside of each pod, or individual LEDs. The LED replacement bulbs would have the same problem with the slots. The wideband really stands out when lights are on! Does anyone have any ideas?
get rid of the WB display, for starters. You don't need it once you've adjusted the carb properly with it. Getting rid of a bright thing near the dim things will help visibility. Do you have any idea what the plastic material over the slots was like? Perhaps it was there to diffuse the light, and keep it from having the bands that make it hard to see things. If so, it probably had a translucent matte texture?
I can remember when I was a fireman some of the older fire trucks 40s-50’s had separate lights mounted on the outside surface of the dashes to illuminate the unlit gauges. They looked cool.
I'd try LED replacements. Looks like the OEM bulb is about 2.5W and 25Lumens, the LED version is 200lumens and less than 2W. You may have to cover part of the light slot with that much light from the LED. Just be sure to ask for traditional LEDs. edit: from the bulb number you posted I assume your car is 12v? If not ignore me.
These at least,look traditional, but you have to buy 10. https://lamptech.com/lamp-1893-led-equivalent-miniature-light-bulb/
I used LEDs in my ‘37 dash - car style, not truck - and got much improvement. The only glitch was finding bulbs that were not too long as well as lighting around the side rather than toward the front.
Assuming you have the correct bulbs (volts and watts) it could be the original plastic lenses had a skirt that hung down to the light slit. This would be so the lens would "bend" the illumination up around the corner and across the gauge face in sort of a fiberoptic effect. If you by chance have replacement clock/gauge lenses that don't arch all the way down to pick up light from the slit, that might be the problem.
!2 volts. not 6. I will check on the lenses, they were an off white, at least the one I had that didn't crumble when I moved it. Going to try the LED version of the 1893 if it has side LED's.
Old 36 Ford I did we used plastic sheet from the hobby shop to replace the discolored lens material. Worked fine.
Did you spray the inside of the housing with white or silver paint? That would help spread the light supplied, around the whole backside of the gauge face. It should then help light up the front.