Ok thanks for the info.The insides are cloudy? Is it water vapour or dust? Either one will cause significant loss of light output...but if the seals are gone (water)...your idea to replace the units entirely may be the right one. If it's just dust, you could remove them and swish a couple of rounds of methanol in it to try to clean the dust out.
In either case, removing the lights isn't terribly difficult, but the bumper does come off easily enough. CARiD has some cheap aftermarket units.