Our marine toilet is a manual model. You do your business in the bowl like normal toilets, but then you use the hand pump on the side to pump it out. There's a little lever on the right (just above the T handle for the pump) that allows you to pump "wet" or "dry". Wet means that sea water is pumped in and washes down the bowl as you pump out the waste. Dry means that the pumping action just pumps out the waste. Our normal practice is to pump dry and use freshwater from the sink/shower to "flush" the bowl. That has worked pretty well so far.
But now the handle doesn't pump and I came home to hit the web and find out what my choices are. Below is the parts diagram from Jabsco.
As you can see, the marine toilet is a relatively simple device, but it does have a lot of rubber seals, o-rings and gaskets that can be replaced. Interestingly, diagnosing and buying the parts individually is the most expensive way to go. There are "rebuild" kits that are sold with all the commonly replaced parts in them. The procedures don't seem too difficult but for only a few $$ more, you can just buy a replacement pump assembly already assembled with all new seals, gaskets and o-rings. That seems to be the way to go as the procedure to replace the unit is fairly simple, and this all has to be done while the boat is sloshing around in the water.
So a replacement pump assembly along with an extra Joker valve (allows the shit to only flow one way - and something I should have been replacing each year) are on their way from Amazon.
Since a through-hull (boat speak for hole in the boat below the waterline) is involved, I also got a couple of plugs... just in case!
To be continued...