I recently replaced my heated switches and the lights were dim. I replaced the filament bulb with a LED and replaced the dim orange LEDs with red.
I cut two small circles of perfboard from Radio Shack, then epoxied them into the back of the seat switched where the filament bulb socket used to reside. I epoxied the green LED to the center of the perfboard and then soldered 220Ω resistors to each end and to the circuit board.
In the dark:
I really enjoy that I can see them in daylight now as well.