I have a low flush toilet that has a problem. When you flush it instead of pushing the handle down and walking away you have to stand there and wait for the water to drain. I took the tank top off and looked in side. This is the kind of toilet that has the floater that is a cylinder on the input water supply shaft that rises as the water enters the tank. This is on the left as you look in the toilet. The handle is connected via a steel chain to the flapper which is on the overflow pipe.
When I push the handle down it pulls up the flapper however if I let go of the handle the flapper falls back down over the flush valve seat. I tried replacing the flapper but to no avail?

Easy fix! Sounds like your flapper linkage needs adjusting.
With the flapper seated the linkage wants to have 1/4" of play. Too much play and the flapper doesn't get pulled back enough giving you a short flush. Too tight and it lets water seep past the flapper. I adjust the chain by the link and if it needs fine tuning, I bend the flush lever rod a bit untill I have the desired play in the linkage. One more thing about a flapper. you will see where the old flapper hooks onto the base of the white overflow tube. On a older type with no hooks the flapper has a ring that slips down over the overflow tube to the seat. If your tank has hooks, take a sharp knife or scissors and cut the neoprene ring off on the marks provided and hook the flapper on the hooks. Leaving the ring on will interfere with the flush. The water level in your tank should be 3/8 to 1/2" below the top of the overflow tube when the tank's filled. Hope this helps and thank you for rating my reply. Tom
The ring has been cut off , still does not work , flapper seems too heavy and unbalanced --- front heavy