On 3' or 4' wide walkways I could saw cut and lift section of slaps and
adjust for level.

On larger patio slaps, its too heavy for me to lift. Six slaps of concrete
about 8'x8' each with 2x4 redwood in-between that were installed by a
contractor. Over the years, the slaps settled at different rates as much as
2" vertical distance at the redwood interface. I've seen contractors pump
material into the concrete to adjust the height but that is not exactly a
DIY project. Other than cutting it up into 4'x4' slaps, is there another way
to do it without heavy equipment?