Jim:"in a peculiar way, Frank is right - every man does have a star. the star of one's honesty. and you spend your life groping for it, but once its out it never lights again." what is jim referring to?

Jim emphasizes the necessity for honesty in one's life. The reference, obviously, is to the dishonesty of Joe Keller when he ships defective parts as if they were okay, thus causing the deaths of pilots. No one will ever trust him again.