Dim Suburban instrument cluster bulbs

I have a 1990 Suburban and the instrument cluster lamps are so dim I can't see them at night. This has become steadily worse over many years. I replaced the lamps with new ones from the dealer, but even with a 12VDC bench supply they only glow a dull orange, not bright.

Any ideas? Are there LED replacements that anyone knows of?

Is something else going on?

Thanks!

If you have good ground and 12 volts to them they should be bright.
Headlight switch controls voltage/brightness to them.

Have you checked the ground?