Alan, just joined DealerEdge. What a great opportunity to openly discuss everyday issues.
Maybe you could have your technician in your office, describe what you think is the situation, ask him what he thinks is the situation (always act as an investigator instead of assuming one side of the story is right), then get up out of your chair and ask him to sit in your chair for a moment and decide what course of action he would take to correct the concerns. If he makes a decision that you and your manangement team can live with, write up an agreement between you and he, then have a contigency plan that he and you come up with and follow it to the letter.
Perhaps if he feels that he is being asked to determine his fate, he will better understand the magnitude of the situation and make a choice that all can live with. As difficult as it may be to find good quality guys in your market, it may be even more difficult to terminate him and "train" a new person once you find them.
RK