Remove
I have not done this, but all other setee tops are removeable by removing the visible screws, then look in the space behind the cushions, there are screws driven in from the back holding the plywoon in place, I would also check in the head, under the vaniity, possibly one or two there. When the screws are removed, the top should come off for access to the tank.Good luckJK sv 50/50