Toilet seal

We had issues with ours, (ball was catching the rear edge of the seal & pulling it down).
I separated the bowl from the base, removed the seal, & found it was quite deformed.
I cleaned the seal with a used toothbrush and Dollar General scouring sponge.
I reassembled rotating the seal 90° clockwise. It still failed to hold water, so I poured in several bowls of straight HOT tap water over two days.
Lo & behold after 3 days it now holds water just fine. I will be ordering a spare for just in case not a priority though.
BTW I spent a bit of time fiddling with the alignment to get a symmetrical fit to prevent the ball grabbing the seal again.

Step on the lever and pick the seal out from the inside. Nothing to take apart. Usually can just be cleaned up and put back. Most any RV place has new ones.

I removed the seal and cleaned it good then sprayed with silicone. It has been holding water since. Not hard to do.

I bought a trailer that had sat for 4 yrs here in Az and that seal wouldn't hold water for 15 min. Bought some toilet seal conditioner @ local rv store and 1.5 yrs later it holds till it evaporates Month or so. This stuff woeks well. It softens the seal.

As soon as you do yours let us know, I have to do mine, won't hold water unless I use ploumbers grease on the seal.

Pull the old one out, clean, put the new one in-
http://bryantrv.com/docs2/docs/dometic310ballseal.pdf

(I just added a few new service manuals and tip sheets at http://bryantrv.com/docs.html and this happened to be one of them.)