I saw Terry review of this toilet elsewhere so came here to ask my question. I am trying to install a new flush valve. The valve has to be inserted into the hole and then rotated to lock in place. I have tried putting olive oil and tried silicon grease on the gasket to get it to rotate, as suggested elsewhere, but cannot get it to turn. I have read comments from a couple other sites saying "difficult but not impossible" but I have been unsuccessful so far. Can you suggest anything more? This should be such an easy job except for rotating the valve into place. Thanks!