As Kidkrz says, the TM Technical Library has a number of tutorials regarding the bag seals. There are also a number of tutorials regarding the Thetford toilet. This one in particular
https://www.trailmanorowners.com/for...ead.php?t=5889
should help in re-attaching the toilet to the floor.
As you may recall, there is no space under the floor for a conventional black water tank. However, a number of our members have removed the Thetford and replaced it with a Sealand M-28, which has the black tank above the floor. Again, there is info in the Library, but in this case you will find even more info simply by doing a search for "Sealand". It has been one of our most discussed topics.
Since Thetford has stopped making the recirc toilet and all parts for it, I think TM owners have become the world's supply of the toilets and their parts.
Bill