@twisted
If the lens is glass and the reflector is metal, try some acetone (or nail polish remover) to try and coax the sealant out. I'm not sure that this'll work, so proceed with caution and at your own risk. Alternatively, you could try a surgery scalpel and try to cut the sealant off (It's a laborious process, but safer for the headlight. Not so sure for your fingers though...^o))
Hope this helps. As usual, be careful with solvents and blades.
Sami