You should be able to re-use both seals. Mine have been in and out several times.
Leave the grub screws in the ring but not protruding outside of it.. You might want to tighten up a couple of opposite ones pretty quick once you have it all in position.
The trick is to lube the lower O-ring with something rubber friendly such as Vaseline, but keep the upper, outer seal dry or it will just flip out of place too easily.. Carefully wipe it clean but don't stretch it.
I forget the exact orientation of the upper lip seal now, but it should be self explanatory when you have it in your hand.
It is a complete tease to get into place, but just chill and be prepared for it to take several goes before it all just pops into place. It will need a nice "deliberate" square blow to get it in, but nothing so forceful as to do any damage to anything.
Just take your time and consider it some kind of meditational therapy..
