Switch under the lights - not sure what you mean. If it's the door switches - take them out and give them a good clean. A little steel wool or very fine wet and dry sandpaper on the contacts and they should make a good connected circuit. You can buy replacement door switches as they were a generic design and a lot of manufacturers used them. I don't recall the diffuser in the instrument clusters being coloured but some did have a paint on them. Do not remove the cluster bezel and clear cover to access anything. You have to pull the whole instrument/dash insert out to access the speedo cluster (you might have already got this far - just ignore me lol) Once it's out you can remove all of the warning light and back light wedges.

Check this image from another thread for the instrument + back light wedges (the green ones are backlighting)