That toilet is original equipment
....replace the whole thing. The Groco HE model was made obsolete by the current
HF model more than 10 years ago. You could replace just the pump with an HF, but the total cost for the "upgrade kit" (new pump plus the necessary adapter to make it fit the base) will cost you almost twice as much as a complete new Jabsco manual toilet. Jabsco isn't a toilet I'd recommend, but it'll last you at least a couple of years...and with as many "boat bucks" as your boat needs, that's all you need to spend right now.
Replace all the hoses too--and get rid of that cartridge in the flush water inlet hose. It requires frequent replacement of a chemical intended to reduce sea water odor
. They don't work
very well, replacing the chemical can be messy, and the chemical can react negatively with holding tank
Sanitation hose is the one thing you do NOT want "go cheap" on if you only want to do that job once...cheap sanitation hose cam permeate with odor
in less than a year.
If you'd like some one-on-one help in spec'ing out what you need and how to do it right the first time (always cheaper and easier than doing it over), you're welcome to send me an email
"If you can't explain it to a six year old, you don't completely understand it yourself."