I just found the answer to this riddle. Once you unscrew the two screws at the bottom, just separate the white plastic cover from the tank (around the handle) and it will come off, work your way around the border of the tank with a knife or screwdriver. Be sure to separate it from both sides and the tank will be exposed.
Hope it works for you... good luck!
Mauricio Delgado (Costa Rica), August 2009