Let me repeat this.
I have sold 300 of the TOTO Aquia toilets. They are nearly perfect as far as I can tell. Less then 1% returns, which for construction, you could argue that it's about as perfect as you're ever going to get.
When there has been an installation error, we've been able to go to the homeowners location and readjust the tank bolts and everyting will be fine.
We tell our customers, that since the black rubber seal between tank and bowl is of firmer rubber then the sponge rubber gaskets that other toilets use, that it requires slowing down just a bit, and using a screwdriver back and forth on both sides, tightening the tank to the bowl much like you would for the torquing of the bolts when reinstalling a head to a motor engine. You can't just crank one side of the tank down too far pulling it off center and expect a good result. Slow down and tighten evenly.
And that's why out of 300 toilets sold, there were 297 that worked perfectly.
The homeowners are doing a better job than the plumbers by the way. They tend to read the instructions and will listen to advice. If they want to have their own plumber do the installation, we will talk that plumber through the installation for them. Most of the time, their plumber is too impatient though. We can take the same toilet, (and we have) and install it perfectly. It's pretty sad when plumbers can only do a few things right.
But then, it opens up complete markets for people that have brains.