As I recall, assuming that based on the dates the lights are BOSCH or Hella OE there is a foam gasket the the lens lays against and there are about six or eight galvanized steel clips the secure the lens in place while exerting compression on the glass lens's foam gasket.


Probably best to get them off the car in order to get things done right without breaking anything in the process.



Especially with the OE Euro lights, moisture in the housing is a real problem, the mirrored working surface of the actual reflectors are a vapor deposited aluminum, highly susceptible to degradation when high temps and moisture combine.


Good luck with it