The following worked well for me
- remove the instruments (noting the connections) and dissemble
- clean up inside and repaint the reflecting internal surfaces using a white but not too glossy white paint
- leave the blue plastic bulb dome filters
- install warm white LEDS (provide significantly more light lumens)
A too glossy or reflective paint leads to uneven illumination. I didn’t try removing the filters but this would . The switch dim function no longer makes a significant difference but no big sacrifice.
It’s worth the effort and results in a much improved illumination but still a classic look.

 

Restoration of gauges is most rewarding ~ My fuel gauge finished.

 

Looks like they repainted the whole face, or did it just clean up really nice ?
If it's in good shape, do they redo the face anyway ?

 

I merely cleaned it with a photographic puffer brush. Most important thing is to ensure that the glass is spotless inside & out or dust, fingerprints etc. shows when lit. These are the original gauges from my car. I wrote an article at David's request for the Register Magazine. You will find a precis of that in my thread attached to my signature here. I had a black anti glass rattle seal manufactured. I got a medical "rubber" company to extrude 5 metres of 2.5mm OD x 1mm ID black silicone tubing (perfect replacement seal)

See from post No 31 in my thread attached to signature for story.

Job done by yours truly & my grunt work man who is a star. He worked hard on getting the right matt finish on the black surrounds. He is a spray painting genius.

 

Very often it's dirty Glass on the interior of the gauges, with the speedo & rev' there's a blue plastic filter that also gets dirty (and if a more powerful bulb has been fitted that can burn the filter).