I have an american standard 1.6 gal toilet that flushes intermittetly.
I have to hold the handle down until all the water from the tank empties into the bowl and the flapper comes down, but even using this method the toilet fails to flush.
For instance if I try to flush the toilet with nothing else in there but water sometimes it flushes, and sometimes the water just swirls gets closer to the drain but then it stops swirling and starts filling back up as if it had flushed. This occurs completely at random.
Our previous toilet developed this problem gradually until one day it stopped flushing altogether, and then we got this new one but the problem remains.