Charging system check? Bulkhead connector terminals? Remove the cluster and clean the inner reflective surfaces, which are probably dusty? Good grounds to the body? Do the brightness checks at a "fast idle" engine speed. 20mg Lutein w/5mcg Zeaxanthin daily for a month (sounds unusual, but worked for me).
What bulbs did you use?
As a note, the instrument panel lights are not supposed to be brighter than what you see through the windshield, as in about 60-70% of max brightness so they are bright enough to see clearly, but not too bright. This can become an issue as one ages, relating to "high contrast light sensitivity", from my own experiences. "Bright lights" against darkness, for example. Especially with modern headlights that are more like looking at a Tensor reading light times 2-4.
Just some thoughts,
CBODY67