I thought I had better start a new thread as this aspect of my situation now has nothing to do with Water Pump Sealant

I am looking for guidance on installing the oil seal into my water pump. Open end points to the oil side of the pump - got that. The instructions say to tap into place using a hammer and a 19mm socket. This is where I don't get it.

The seal just drops in with no effort. I am tapping it into what and how far?

The seal appears to be the correct size and does marry up to the water seal ok.

I just need some deja vu