2650 CdW black water vacuum valve
I attached a picture of my black water vacuum valve. It was in the cabinet beside and under the bathroom sink. One hose comes from the outside attachment and the other goes down to the black water tank nozzle. Talking to a tech he said to fill your black water tank to the top with fresh water and let it sit for a few days to make sure no toilet paper hardened on the nozzle. After that it is probably the vacuum valve. You might try banging it but he has never seen that work. I'm still working on mine. Tried filling the tank and a little compressed air but nothing is moving anything. In process of getting it replaced.