1990 40hp Johnson power tilt..need help please

[Shivesy]

Helpin dad rebuild his power tilt on the Johnson motor today. To be honest we really dont know what we are doing but feel we were doing things correctly. We bought a o-ring and seal kit and tore it apart and replaced most of the seals. We put it back together and added some hydraulic jack oil and the darn thing is working. The problem we are having is that the upoer wiper seal that we installed in the cap nut keeps popping out. Then oil leaks out also. How do wekeep the seal in place and what is the proper way to fill the tilt with oil. Thanks guys