I need to re-seat a run of sandstone paving that forms the top step at the edge of a lawn. Its been in place for around 14years, and all the stones along the top are loose. Originally there was just a brick wall in place. The wall was left in place, and the slabs laid on top. Over time the base behind the wall has dropped, and so the slabs are loose, and wobbling. I'm not sure what is under the part at the back of the wall, there seems to be at least 2-3in of mortar bed, but I'm not sure what is under that. I'd appreciate suggestions for how to re-seat these stones that will give a long term stability. (The lower stepslabs are solid and just need regrouting)
