I dug down to the header (distribution box) to have a look then opened a leach line. The leach line is plugged with muck. Is it typical to have a line full off muck or should they be partially hollow still. I'll didn't dig a line at the end today to see what's in there. Yes there is a beautiful tree growing right beside the leach bed and I'm sure that's one of my problems. No cast iron it is 20 years old and they used plastic header with clay tiles.