I've gotten into the habit of polishing the paint off the outer edge of the lip seal with my wire wheel buffer. That helps the seal slide in without having to hammer on it so hard. LocTite on the outer edge lubes it going in, and then leakproofs it around the outside. once it cures. If you haven't disturbed the relationship of the cover to the engine, centering it probably won't be necessary.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!