Fixing a running toilet was so much easier before gravity flow took over everything. I even bought a Japanese toilet recently because the gravity flow device in my standard American toilet just would.not.seal., even after replacing it. Thing was driving me nuts.
So instead, I had my dad install a toilet for me! Go dad.
I wish, but I didn't have electric hookup available and didn't want to call in an electrician, so it's a pretty standard toilet aside from the flushing system (which works perfectly and doesn't run!).