I put a new joker valve (aptly named) 2 days ago. yesterday, I find that the bowl is full of nasty water
again. the 410's holding tanks
are well above the toilet, which puts a lot of pressure on the joker valve since there is no way to fully evacuate the waste line.
I'm thinking of adding a flapper check valve, but not convinced that that would permanently solve the problem. i'd love to hear other solutions.