If the internal plastic lens has gone dark, due to the ultra violet light or heat from the bulbs, then the llens can be either changed with a new item from Fords or gently take off the clips holding the outside lens on. Remove this outer lens and gently remove the inner lens. You can try to clean this lens with 'Brasso' or plastic polish. Make sure you get all the cleaner off the lens before you put back in the light unit.
Put the unit back together in the reverse order of taking apart.
Your light should now give the original light output.
You can now try the uprated bulbs to finish off but eventually you will need to go through the cleaning process again. Good luck.
DaveL
February 2007