Hi Everyone. Well, after 15 years the RV-Dreams Community Forum is coming to an end. Since it began in August 2005, we've had 58 Million page views, 124,000 posts, and we've spent about $15,000 to keep this valuable resource for RVers free and open. But since we are now off the road and have settled down for the next chapter of our lives, we are taking the Forum down effective June 30, 2021. It has been a tough decision, but it is now time.
We want to thank all of our members for their participation and input over the years, and we want to especially thank those that have acted as Moderators for us during our amazing journey living and traveling in our RV and growing the RV-Dreams Family. We will be forever proud to have been founders of this Forum and to have been supported by such a wonderful community. Thank you all!!
While I can't say for sure that I've dealt with the Sealand 511, if it is like our Dometic toilet, you might consider replacing the spring assembly.
The spring assembly will look something like this image above, and it is fairly easy to replace. At least, that would be the first thing I would try replacing. Even if the spring isn't the problem, it never hurts to have a spare spring stored away in the RV. I generally have at least 1, if not 2 or 3 springs stored away.
I don't know if this will help, but someone posted some helpful information at IRV2.