Peggy,I have your book and it has been very helpful. However, I am now totally frustrated. I have a 1996 37.5 Legand Hunter with a factory installed Jabsco toilet. This past winter I replaced the old black hose with new white hose, I had a new pump put in, I backwashed the air vent and I'm still having a problem. Everything seems to be working okay but I keep getting a back flow into the toilet bowl after the boat sits idle for a week or two. I ask the guy that installed the new pump if he replaced the joker valve and he said he did. I'm not sure if you are familar with the set up on my particular boat but the bottom of the holding tank is actual higher than the toilet. This means that if you don't get everything flushed to the tank it will come back to the toilet. If the joker valve is doing it's job the waste should not get back into the toilet. Therefore I have to believe there is a problem with the joker valve. I'm ready to yank the damn Jabsco out and install a new toilet if I have to so any ideas would be appreciated. I'm tired of everything in the boat swelling.TomS/V At Last