[missourijan]

Ok, I'm going to offer something maybe you haven't thought of. Don't know if you are fulltimers or not but we are and I have found that when you are dumping (and the water is turned off to the rv), take the time to clean the "tube" going down to the tank. You don't have to be fulltimers and use that toilet all the time for "stuff" to grow in the tube, like pink mold & icky stuff. It will take more than one cleaning to get all the "stuff" off the tube wall. I use something strong like Awesome from the Dollar store and scrub that tube with the toilet brush. You also need to have the toilet brush on twine so you don't lose it, I stand on the end of the twine. And you need a good flashlight to see down there. Cleaning the tube makes a world of difference with smell.
Good luck!