Usually you will not have to replace the valve.
Most issues with leaking valves are caused by the cable sticking and not closing the blade on the valve or crud buildup on the blade of the valve and not seating properly.
First thing to do is run your unit up on a couple of planks on the valve discharge side to allow any remaining grey water to run away from the valve assembly to the other side of the tank,,,yes there is still some of that crap in your tank even after draining.
If you have an enclosed under belly,drop enough of the Coroplast to locate your tanks and valves.
Have someone pull open and close the valve cable in question so you know which thank to work on..
There are 4 bolts and nuts holding the valve in the pipe/ tank assembly..they are 7/16 th nuts..remove nuts and bolts, pull pipe back away from valve and take out valve?...There will be 2 rubber o rings on valve. Do Not loose them and make sure they go back into assembly.
Once out ,you can loosen up set screw on cable at valve, pull cable out and check to see if cable moves freely, clean blade assembly and apply grease to the steel shaft...this shaft slides the blade assembly and goes through a rubber sleeve, this gets dry and the assembly valve sticks, grease it and move it back and forth by hand until it moves freely.
If it’s the cable that’s sticking you can remove from compartment and soak cable and cable sleeve in transmission fluid for a few minutes to lube
Re- install and check operation of movement before putting coroplast back into place..
This process is more time consuming than difficult.
Good Luck.
