Thanks for the replies. To clarify, my black tank is full. Plenty of liquid in the tank. Either I have a clog between the bayonet valve and the macerator pump, or the pump itself is not pumping, or the line from the pump to the main dump (on the other side of the coach) is clogged. My main concern is how to remove the macerator pump and how to empty the black tank without making a huge nasty mess on me and in the compartment where the bayonet valve and macerator pump are located. THEN I can deal with the maintenance/repair to the macerator pump. Any advice is welcome.