Hi Robert,
there is Larrys great video regarding timing belt and sealing ring change:
https://www.youtube.com/watch?v=CCPXoCrK9_8 At about 18:40 to 19:15 you can see how the sealing is being mounted properly by using a nut as a termination inserting tool.
These things are important:
Clean shaft area before removing the old one and especially prior to install the new one.
Avoid any scratches and polish the shoulder the sealing lid runs on.
Lubricate as well the inner sealing lid as well as the outer cylindrical diameter, because both areas are having a sealing function. One static, one dynamic.
Press in the ring by using an inserting tool that leads to parallel and evenly spread force.
By the way, Larry refers to the SCORE community

A remarkable video! In the beginning he is talking about a K6A Engine, but he corrects it in the comments. It's a F6A engine. Have fun and success!
Martin