Auto body repair & detailing: Moisture in headlights, mercury marquis, crask

Question
Considering purchase of low mileage 1998 Mercury Marquis.......noticed accumulation of moisture inside headlight lens on one headlamp.  Successfully siphoned moisture out, then after another local rain (three days later) moisture is back. How does moisture enter said headlight and how do we fix it ?

Answer
  hi haarold,
     it is possible that it water is getting in around the seal where the bulb sets in the housing or there may be a crask or a seam in the housing is leaking. about all i can tell you is run some water on it and see if you can tell wjere it is getting in. and apply a silocone sealer . thanks for writing.
                                            dave.......