Remove your grow lamp from your hood/fixture. Check the base of the grow lamp for signs of arcing (see photos below). If there are any signs of arcing, black carbon buildup, bluing of the metal, or discoloration, you should replace the socket. This is an inexpensive part to replace and can be obtained at your local grow shop. Failure to replace the socket can result in catastrophic lamp, socket, and/or ballast failures. It does not make sense to destroy a $400 system over a $15 socket.
Make sure the reflector and lens are clean. Any dust/dirt build up can decrease the intensity of your light, ultimately affecting the quality of your plant growth.
Also make sure the lamp is clean. Glass wipes work perfectly for this application. Squeeze out any excess moisture and wipe down the reflector, lens, and lamp. DO NOT WIPE THE SOCKET OR THE BASE OF THE LAMP.
To finish, wipe everything down with a clean, dry, lint-free cloth or let everything completely air dry.
EXAMPLES OF ARCING DAMAGE These three images show examples of arcing that caused lamp failure. Notice the base of the lamp and the socket have been welded together due to the intense heat produced by the arc.
Notice the discoloration on the base seen above. This is a sign of arcing occurring inside a socket.