I have a single piece toilet that is probably about 25 years old. The unit itself is solid but the flushing mechanism is poor in that it takes several pushes on the handle to get the unit to fully flush. I have never worked with this kind of unit and the replacement parts for the flush mechanism seem incompatible. Once the flapper is fully raised, the unit flushes fine.

This is Florida rental property and the elderly residents to whom we typically rent, are having difficulty with this. Before I go ahead and replace the unit, I am hoping that someone out there is familiar with these type of units from which I could get some suggestions on possible repairs.