totally dismantle the cistern. The cistern should be screwed to the back wall with two screws and connected to the pan with two nuts . it would be safer to also buy a new connection kit comprising of plate , bolts and 'doughnut' rubber seal. be sure to evenly tighten the bolts when re assembling so that the cistern does not appear to be lop sided and don't over tighen either.
Maximo
July 2008