[Buster and Sandra]

It's really not a hard job to replace these valves. I had to replace one and clean another, but, the best tip I found on this forum was to lower the front of my rig as low as possble before beginning the work. This allows any residual fluids to go to the back of the tank away from the valve. This made for an almost mess free change.
The first time I was going to change the black water valve I bought a valterra valve, but, when I got the old valve out I found it was just full of toilet paper in the groove the valve slides through. I cleaned it out really well and re-installed the valve. Worked perfectly until we traded in a few years later and I still have a spare valve