I have an American Standard toilet that came with a 3 inch flapper inside. The problem is that since the beginning the flapper never closed properly. It's the right size to block the hole, but it seems as though the handles on the flapper (the 2 attachment prongs) are not long enough, so when you install it, the actual circular part of the flapper is slightly off centre because the handles aren't long enough to extend the circular part to fully cover the hole.
What should I do? Since I am assuming buying another flapper will just have the same problem as the length of the prongs is the same for all flappers.
It's flushing properly but has a bit of space open so it keeps letting water through from time to time making noise. Toilet is 4 years old.