40 year old aggregate pool deck with circle drain system that basically forms an L around the two deck sides of my rectangular pool eventually running out to a greenbelt behind. Deck is in relatively good shape, but over time it seems that the slope of system is not what it once was. Water does drain fine during rain and otherwise, but I think the section of concrete at the 90 degree angle of the L may have settled a bit over time. I see water in pipe in that drain hole and the two adjacent ones. Is there a way to fix this lack of slope in that section without totally ripping out the concrete? Hopefully this makes sense to someone.