First replace the toilet
The average lifespan of a manual marine toilet is 5-7 years...yours is 23 years old--it's worn out. You'll spend more money trying to repair it, with only marginal results, than you'll spend on a new one. No, there is no "one size fits all" kit to update/upgrade a sanitation system. There are too many choices, and the right choices for each boat takes a number of factors into account. So each component--the toilet, the tank, hose, any optional componts, and fittings--must be individually selected to fit both the boat and the owner's needs/budget. The first step--even before you replace the toilet--is learning a little about marine sanitation systems--the laws, the equipment and how it works, etc--even the terminology. The best place to start is with the article in the link that I've provided. You'll find additional information you can use in the articles in the Head Mistress forum Reference Library, on the forum homepage right here on this site. All of the above won't teach you everything you need to know, but it will teach you enough to ask intelligent (not that yours aren't) questions about what you need and how to install it on your boat. And I'll be glad to help you spec it all out.
