Disclaimer: If you don’t have an RV, this probably won’t be interesting to you.
Recently our toilet stopped holding water. The seal had obviously went bad and stopped “sealing”. I called Thetford and they sent us a new valve seal under warranty. So we had to put that thing on this past week. It wasn’t terrible, just kind of gross.
First, if you’re going to do this: drain and rinse your black tank! Then turn the water off. And make as much working room as possible.
The new valve came with instructions on how to remove the toilet and take it apart. They were pretty straight forward. I do recommend having a little Tupperware container nearby to cover the hole.
We got ours in and got the toilet back in place with no snafus. Good luck if you ever have to do this!