I've used my Dometic 310 about 60 days; in the last week, the spring tension on the foot pedal dramatically lessened. The ball still seals but sometimes I have to let the pedal "spring up" rather than just raising it. I don't know what happened to the spring tension, and I don't want it to break and be unusable. It used to close with a really loud THUNK no matter what I did, and now there is little sound at all, with the obviously lessened spring tension.
What should I do?
Actually it wasn't the ball seal I was worrying about, it was the tension required to push the pedal. However, the seal is also not working that well, which makes sense given the pedal pressure problem, if it is the pedal that is supposed to cause the seal to seal.
I had a general water pressure problem (pressure just disappeared) that turned out to be an air bubble in the water piping, similar to vapor lock that I used to get in a particular carburetor when it was hot outside. To fix that, I shut off the city water supply, opened all the faucets, drained the water, then, leaving all the faucets open, turned back on the city water and let it run. After it was running really well I then closed up the faucets again and had water pressure. But that has not worked yet with the toilet. I have enough to flush but it's not what it was. If I find out anything else I'll let you know.
I got the air bubble in the pipe because I shut off the water during the afternoon when it is 108 outside; it was expanding and I was afraid I'd burst a pipe. I'd let the pressure off, and I assume that's how air got in there.
Have you found a solution to the toilet problem? If you do, we would like to know it. We also have a Dometic 310 and it has not closed properly since we got it. We tried using a spa lubricant on the seal and that would work for a couple of weeks. We were then told by a service tech to use the cheapest vaseline we could find. That doesn't work well either. The only thing that works well is to push the ball closed with the finger.
We bought what is supposed to be a luxury fifth wheel. Why it has what a dealer called an entry level toilet, I don't know, but we are not very impressed with it. We don't know if we can upgrade and have the warranty cover the cost up to the cost of a new Dometic 310