Head "rebuild" or "repair" kits
Are available for all current model toilets...most of 'em right on the shelf at West Marine, BOAT/US etc. If your boat is old enough to have a Mansfield (which later became SeaLand) 751 or 752, both those toilets are so obsolete that no parts have been available for them for at least 5 years, but Par/Jabsco does offer a "universal" kit that has most of the needed parts. However, any toilet that old is overdue for replacement...I wouldn't spend the monety for any parts.We recommend putting a kit in every 2-3 years. NEVER replace only a single worn out seal or valve...'cuz if one is totally gone, the rest are badly worn and something else will fail shortly--and it won't happen when the bowl is empty!