Recently we started getting backflow from the septic in the house and around the inspection hole of the septic tank. We found the septic to be very full and had it pumped. Although the tank was in good shape the pumping service said when he tried to shoot water down the line to the distribution box, the water came back out. He said the system lines might be plugged. When we tried to snake the line from the tank all we got was black slime. We dug down to the line going out of the septic to the distribution box and found the line was not even connected, but was 8 inches below the septic outlet. There is no telling how long it has been in this condition. As time progressed we found the distribution box. What are the chances the rest of the system is ok and we’d only have to replace the line from the septic to the distribution box? It appears the box has dropped several inches also. Can we install an elbow to the box to bring up the line to the septic or would this cause a problem? Thanks