“What would be a safe way to tap it in? Do the 2 recesses go down? Should I lube it (saw perm aviation sealant on you tube)”
No sealant required anywhere for this, notches up, machined side down, lightly lube I.D. of o-ring to help fit over crank, don’t tap as Dale said, some guys use a piece of pvc exact size as carbon seal so even pressure is applied all the way around to avoid breakage, then gently push down.
