Has anyone successfully fixed this problem? Any experience or suggestions would be welcome.

The cable has pulled out of the back side of the handle assembly just behind the control panel. The cable is supposed to be held in place by crimps that were placed there but it pushed out of the end when closing the valve (pushing in on the handle). We can get it to close the valve if I hold onto the sheath of the cable with a pliers while the DW pushes in on the handle.

The valve itself was opening and closing with difficulty so a 1/2 cup or so of canola oil was added to the black tank after the last dump. The valve now seems to open and close more easily.

I attempted to re-crimp the handle assembly on to the cable with a vise grip pliers but this was not successful.

TIA for any help.

look at the posting last week black water valve

Time to replace the cable. Absolute worst part of the job is laying on your back taking down the coroplast to get to that end of the cable. Its not a difficult job & while at it you can probably align it so it operates easier.