Bulb melting in socket in Driving Lamp Ass'y

Hi
As i'm new to the site i've searched numerous topics to find out if anybody has problems with the day light assembly, since the bulbs for the day lights melt into the sockets and eventually need to replace the complete housing. At $400/ea. Canadian it's very irrititating and expensive. My mechanic seals the housing to prevent water from infiltrating. Is this part of the problem since they are always on and eventually melt into the socket? Any help would be appreciated