The following is from a letter by the Chafetz Chaim (Rabbi Yisrael Meir Kagen HaKohain):
…Presently it is difficult to find Kohanim who know the laws and practices of the Temple Service fully. How disheartening and embarrassing. It sadly indicates that our prayers for the Temple and the Service are merely lip service, not real or heartfelt. For if we really desired it to come, we would prepare and make ready for it.
Therefore my brothers, it is incumbent upon us to…further the knowledge of the Temple and its Service. Particularly the Kohanim and the Levites, who are most directly involved in this Torah Mitzvah, for they will be the first to be asked, “why didn’t you prepare for the Temple Service?”