Toto toilet's flapper closes after I release the trip lever.
I have had a Toto ultramax toilet 1.6GPF with sanagloss for about 4 years. Now, when I flush the toilet, the flapper with chain closes right after I release the trip lever, leaving more than half of water amount in the tank, which results in a week flush. To make the flush effective, I have to hold the trip lever down until almost all water leaves the tank. Then release the lever and the flapper closes.
I had to show guests this way of flushing when they came to my home. Would anyone know how to fix the problem?
Any input is greatly appreciated.