The Throne Room

All boaters give a knowing smile or nod when a fellow boater mentions they have a problem with their toilet.

It just one of those things. Boaters know their shit. 

Literally. 

Behold. The mighty Jabsco.

Boogie Nights is fitted with a cheap as chips Jabsco manual seawater flushing toilet.
It has a holding tank with macerator and valve options to pump directly outside.

The toilet system is fairly simple.

the official technical drawing of the toilet system of this Dehler 36CWS

The toilet itself is also very simple. It is cheap. all the parts are replaceable. And anyone who owns a toilet like this knows that replacement parts WILL be needed.

Being "at one" with ones number ones and twos, especially the way the toilet reacts, knowing the subtle differences or changes in the action of the toilet is all part and parcel of being a boat owner. 

Every year I take the toilet flush apart and change the valves. They're rubber and get furred up with calcium deposits.
Once a month I drop a litre of warm vinegar into the toilet system to help keep the calcium deposits down in the pipework.
Once a week I put a drop of cooking oil into the toilet to keep the flush running smooth and quietly.

Sometimes routine maintenance turns sour and an additional replacement part is required. This is a CHEAP toilet. The very act of taking it apart and putting it back together makes it break.

I have written previously on the matters of the toilet business.
Toilet Humour explains what happens when there's a blockage in a breather pipe and the catalogue of errors that ensued.

Standard service kit. Longer bathroom gloves and the basic Jabsco service kit.
Includes all the rubber valves and spares that might break

Sometimes when taking apart the piston plunger barrel to change the valves, the threads will strip or the plastic will snap and you are left with a spitting and bubbling mess of bodily fluid dripping on to the floor.
A return trip to the chandlery (closed by the time you realise the old part is broken) is then the only option to fetch another spare part. You will go to bed feeling disappointed.
You will wonder if it wouldnt be cheaper to buy a WHOLE NEW TOILET instead.

 Caution - random smutty giggles may be inevitable with following terminology 
when greasing the new pump handle and plunger, the Volvo Penta grease used for the
rubber lips on the propellor shaft non drip stern gland is a good bet.