I noticed a nasty case of green slime behind the outer edges of my sidelights (mk 1) over christmas If you find the same, cure by:

1.take out light assembly, remove connectors & bulbs
2.put a small amount of household bleach on the affected area, leave until the slime goes a grey colour
3. rinse under a tap to wash the crud out! (mind you don't get water inside the assembly!!!)

hey presto! nice clean lenses! (1/00)
I had the same thing on one side of my 93. Just took the lens out by unscrewing the 2 screws and scrubbed with a brush - no more slime or stinky bleach ! :-) (1/00)