Saw YouTube post on cause of this type of toilet leaking/running. Recommendation was to use American Standard seal vs big box store brand. Web search found AS site and ordering was straightforward and arrived within 5 days. Replacement was easy but needed wrench to get better grip on top screw to remove. Needed to reseat top/bottom after a day since still leaked; needed to align top/bottom better. Once did that , good as new after two weeks.