I bought this used 1994 carri-lite RLS 5th wheel and shortly afterward started having trouble with sewer. Black tank won't drain. I tried pulling/pushing the valve (which was already open), tried using the internal "sewer hose" to clean out it thinking maybe TP had plugged it up since I was out of camp chem, tried running a sewer bladder up from the outside thru the drain (which is about 5ft from outlet down side of RV to valve area, tried WD 40 on valve thinking maybe stuck, none of which were effective. It's now full and draining out the bottom of the RV; old owner said only draining out the bottom if was full and came out the vents and previously I found that to be true, so assume still full. Yesterday I used the internal hose and water/crap backed clear up into my toilet; put a huge bottle of camp chem down it to make sure anything there dissolved, now camp chem draining out the bottom on the ground. Only 2 other things I know of are the vents are plugged but I don't know where they are on this (had bus model before) or the valve handle broke off and valve is stuck shut (altho feels like its working). The valve on this model is not accessible like my others have all been where I could just see if broken or unbolt and put a new one on. ANY help would be appreciated. karen