EMOR - PREPARING THE MENORAH - THE REBBI'S MISSION
Aharon was given the mitzvah to יערוך אותו - to set up the Menorah. Not necessarily to light it. Anyone could theoretically do that.
The menorah, we know represents חכמה and we see from here that the main function of the Rebbi or Mechanech is to PREPARE the vessel to be ignited from ANYONE. The goal to is to raise a חכם - What is a chacham? הלומד מכל אדם - as R' Yonah explains (Avos 4.1) One who appreciates and loves חכמה so much that he is eager to learn from anyone and everyone. That is a חכם.
So an expert Rebbi or mechanech's job is to clean out the past negativity and ashes of extinguished lights. So that the oil and wick can be lit in the מנורה הטהור - directly in contact with the vessel with no blockage or separation.
When the vessel is clear, and a fresh thirsty wick is prepared, and fuel is there (perhaps פרפראות - like appetizers for חכמה ?) the talmid is already a חכם and now any wisdom will be easily imparted and absorbed in his eager mind.