That... does not make sense. The camera inside the housing does not change its displacement - only the mass, and the tiny amount of air that it displaces out of the housing is well below the margin of error for measurement. Are you sure you don't have pulley friction throwing off your measurements?
I guess I'll buy a set of tire balancing adhesive weights, plus get an extra set of aluminium arms when I order the housing. It's hard to believe that it is that much more buoyant than the old version though.
I wondered that too so I measured twice... but given the narrowness of the can the string WAS running against the housing.
The housing is bigger than the old one... and that dry dome is a massive volume of air (its a larger diameter than the old wet one too).