I have the exact same model toilet & the ball quit working but luckily it was stuck in the opened position. Since we were taking 2 planned trips with only 2 days between them -- we just used the toilet anyway.
When we got home & I could finally take the toilet apart, I loosened the silver band holding the top on the bottom. I used the ball-cleaning tool (AKA "tongue depressor") and an old toothbrush on the ball, & scrubbed off the 2 seals. Then I applied a good amount of Vaseline to the seals and surfaces of the ball & reassembled the toilet.
Voilá! The toilet worked again. Except...... It still won't hold water. Not a problem with doing #1; a problem with doing #2. So my son came up with the idea to lay a couple of strips of TP in the bowl before using & everything flushes down just fine! Maybe even better than before since there's no "skid marks" in the bowl even!
Just sayin' that the lack of water in the bowl hasn't affected our use any. And I don't notice any odor coming up either, since the ball pretty much covers the opening.
