Toilet Wont hold water in bowl after gasket replacement.

I just pulled apart my SeaLand toilet and replaced all the gaskets. I followed this video https://youtu.be/vi3TRivsNlQ . While I had it on the bench I poured a bottle of water in it. It held water just fine. After I re-installed and used it a couple of times it will not hold water anymore. Here is a video of the plastic ball moving. The water is off for season so I cant show much. It holds water for about a minute.

https://www.youtube.com/watch?v=py3gdeUQS7M



What is the next troubleshooting step? I am thinking replace the ball with this kit ->
http://a.co/6Yet91M