It probably would be better to pull the toilet off the floor and replace the seal from the bottom.
The flat blade toilets had more troubles with the seal leaking past, by design since debris would get stuck into the seal groove underneath, and the flat blade just kind of rested under the seal. Maybe you've already tried to clean the underside of the seal first. Any scratches on the blade allowed a leak also. I think I read somewhere that the flat blade isn't available as a separate part anymore.
Not the same toilet you have, but I did replace the ball seal on ours a few years ago. Took it out and fixed it on the truck tailgate. Replaced the flange gasket at the same time as it was in the seal kit.
Don't use petroleum jelly on the seal, plumbers' grease is the safest lubricant that won't degrade the seal.
