NO Thetford IV manual(foot/hand) RV toilet has a "float". The water valve just opens and water flows into the bowl reservoir tank and then into the bowl. The point is to prevent excess pressure/water volume from spewing out the bowl fill tubes running out the top of the seat area onto the floor. Think of it as a regulator. IF you are talking about the top half and bottom half that is secured with about 8 screws then you just use Butyl to seal and then trim the excess off. There is no reason to disassemble unless you needed to do a thorough cleaning of the base assbly. Doug
PS, Yes, Butyl will do for the Flush tubes over the nozzle ends.