that was the very first thing i checked after i inserted the lamp, and my magnum had no leaks, if yours did, take it back it, is under full warranty.
i used a white chimney smoke pellet to check the four at the same time once they were all connected and up and running. and i had no leaks.
i used the first one for 2 months and was impressed so bought another three, i have four 1000w hps with the hoods in a 10 x 6 room and the even light spread is amazing, compared to my last hoods which were made by a firm called venture lighting and i had 6 x 600w to get the same even spread.
and the magnums are a lot cooler too.
more space in the hood, less time to heat.