If the subfloor is not completely level, “run-off” may occur. This is evident when the corners of the tile are not meeting exactly. The best way to correct this problem is to leave a tile out to be installed later and continue to install the other tile around the opening. It is important not to let the run-off exceed 1/8″. The tile left out must be in a row that is running long. When installing the tile that had been left out, heat this tile from the back and place the corners of the tile into the open space. Press the tile into the adhesive and lay an unheated tile over the heated tile. Apply pressure to compress the unheated tile into the opening and hold it there for a couple of minutes until the heated tile cools and stays flat.