I had a slow, trickling leak from the tank on my early 70s Mansfield. So I replaced the flush valve seal (black snap-on disk) at large rounded end of the "horn" of flush valve (type 208/209). I made sure it was applied evenly, nice and flat, with the tube section seated well to the center hole. Unfortunately, although the leak has slowed, it still trickles a bit. When I put a little downward finger pressure on the “horn,” the leak stops.

Do you think the tank-to-bowl / TTB gasket that the new flush valve seal meets is worn, too? (It’s old, I know that much!) I assume the only way to replace this TTB gasket is to remove the tank (and by the look of the tank bolts, this is not looking to be a pretty task!!!)

Would it do any good to try wipe the TTB face clean and see if that helps the flush valve to seat better?

I would hope the TTB gasket is easy to find. Should I replace anything else…the actual body of the tank/bowl “transition” or whatever it’s called? Thanks for your advice!