Refer to photo showing grate and drain hole. Grate dislodged from it's seating position. The mortar under one of the corners seems to have eroded or fallen off and there is no support so any weight applied to corner causes grate to fall and tilt a couple of millimeters. Is it a matter of filling in the gaps under the tile and up to the border of the pipe with cement or mortar and then reinstalling the grate while cement/mortar is wet and allow to dry? Which cement or mortar should I use?
