a904 stator sealing rings...

Did you inspect the sealing surface and test fit the rings in the drum before you used them?
You asked this before and I mentioned that a lot of air does get by those rings where fluid doesn't nearly as much.
If you have the "thud" on the apply with air you are probably ok.

Believe it or not, Teflon rings are a lot harder on the metal surfaces than the steel rings and in my opinion leak more.