For a Thetford C-200CWE gently lift off the top plastic plate that houses the press switch - it lifts vertically upwards (not at an angle or you will break the plastic mounting pegs) but is usually held down by mastic which needs some force to break the seal. The switch is housed in a rubber "boot" which should keep the switch mechanism dry - check and dry if necessary (to dismantle pry out the rubber switch cover and remove the 2 screws trying not to drop them or the tiny plastic push peg into the cistern!!). Remove the 4 screws holding the exposed plastic plate and the pump (similar to whale) can be seen at the base of a plastic tube clipped to the inside of the cistern - just unclip it and lift it out. At the base you can see the impeller which is almost certainly jammed. It can be freed with a small screwdriver - twiddle it until it seems free and then test it in some water. The whole thing takes about 15 minutes and is very simple - the hardest part is getting the masticked top cover off.
David Alexander, July 2008
