how to dismantle Philips GC9230 Perfect Care steam generator from base?

Philips Perfect Care GC9230 Steam Generator Iron- 1.5 years old. Stopped steaming. Iron has been de-calced on regular basis (several times a week). If water is put into the tank directly--the iron produces steam. Iron gets hot. Pump still makes pumping sound. Water is not being sucked up into the tank. We tried to remove the base to see if there is a blockage. Unable to do so. Any help would be very much appreciated.