I have a cedar deck/pergola that sits on a concrete slab. The deck and pergola are attached to the house with lags. A couple of the 4 x 4s suporting the deck (the joists are about 6 inches off the concrete)are situated on a section of concrete that has sunk about 4 inches toward the house's foundation. Short of tearing up the deck to tear out the sunken concrete, is there any other fix for this problem? Would a slab jacker be able to fix that section? Will the sunken crete cause any long term problems? My basement is very dry now and finished. Thank you.