To Fred1diver and Morgandonor... Both of your toilets are too old to be worth rebuilding.
Needless to say have the correct rebuild kit on hand...1980 vintage Groco IIRC.
I don't know how you can be sure you have the correct rebuild it 'cuz there are THREE version of the Groco manual toilet...it was the HC in 1980, HE came next...and HF is the current version, and it's been updated at least once. You can't just use the current HF rebuild kit on an earlier version...here are the instructions for doing that:
https://www.groco.net/media/file/file/h/c/hc_he_to_hf_upgrade_sheet.pdf And by the time you've spent the money to do all that you're better off just replacing the toilet.
If you're determined to stick with a manual toilet, the Raritan PH SuperFlush is the current version of their PH II, which has been the top rated rated manual toilet since Raritan introduced it in 1983 and still is.
Raritan PH SuperFlush If you're ready to consider upgrading to the "push button" convenience of an electric macerating toilet, the Raritan SeaEra is also a top rate toilet.
Raritan SeaEra Promo Sheet Don't let the list prices of either of these toilets scare you...they're available for a lot less.
[QUOTE="fred1diver, post: 1693609, member: 121574" The head is a Jabsco but not sure on the model...QUOTE]
It's a Jabsco manual toilet (there's only one), but it's definitely NOT the current "Twist 'n' Lock" version, which Jabsco introduced at least 10 years ago.
Jabsco Twist 'n' Lock Manual Toilets A replacement pump should fit, isn't that expensive and is an easy job that only requires removing/replacing two hoses and 4 bolts. All the hoses also need to be replaced and we don't know what condition the holding tank is in. So I'd like to suggest a "Plan B:"
On any boat much smaller than about 30' a self-contained system—an "MSD" portapotty--makes a lot of sense. The "MSD" designation in the model name/number means it has fittings for a pumpout line and vent line, and is designed to be permanently installed (actually just sturdier brackets than portables, so you could still take it off the boat if you absolutely have to), which means that although it's still called a PORTApotty, you don't have to carry anything including urine jugs off the boat to empty it.
A 5-6 gallon model is household height and holds 50-60 flushes...you'd need at least a 30 gal tank to hold that many from a manual marine toilet and I'm not sure a "composter" can hold that much poop and organic material needed to absorb the liquid in solid waster (which, btw is about 75% water). No plumbing needed except a vent line and pumpout hose--so no new holes in the boat...and -0- maintenance needed except for rinsing out the tank--which you can do with a bucket while it's being pumped out. Total cost including the pumpout hose and vent line is about $200--a fraction of what you'd spend for toilet, tank and all the related plumbing needed. And the best part is, you have all the advantages of a toilet and holding tank without giving up a single square foot of storage space.
That's my $.02 worth for both of you...what do y'all think?
--Peggie