Team lead should be technically sound to under stand the effort required to complete a job. In case he finds any irregularity in the job delivery, or the progress is not in good pace. he should consult first with the job holder to understand the road blocker.

He needs to identify the symptoms and need to find the cure. In case situation can be handled with the help of simple help/guidance, provide him. In case delivery are near, and there is no time to train the member. Let him know the situation that you have to take this step and switch the responsibility with other. Once the situation is over, give him to understand where he lack and motivate him to get expertise.