I removed tank again and looked closer. The bolt hole on one one side became slightly oblonged with a small liip on one end.I also removed the flapper assy and inspected that also . looked ok on mounting surface. I added clear siicone on gaskets that mounted to bottome of tank for flapper assy and bolt gaskets. let sit to dry and no ore leaks !!! thanks for your help.I should have looked closer when replacing parts but didnt think the bolt holes would would make a difference but they do !!

Darlene, got pictures?? I don't know what a 'drain threaded insert' is. And what size, specifically, are the plbg parts??

That piece that you are holding is called a "strike". FYI

Valves behind walls determine the brand. Unless walls can be cut open for access. From behind, maybe? Kohler is an excellent brand, so you have some organic issue somewhere else in your system. Diagnosis of your issue should be performed first.