If explaining what you want to the choir has become old hat… demonstrate the idea with a quick visual. The idea will embed itself quickly in the singer’s subconscious and will never fail to unlock a positive result.
For example, I often use a golf swing to illustrate the way an operative word is set up by subordinate words. Taking hold my imaginary golf club, I say the important word at the bottom of the swing, demonstrating the natural gravity of the phrase toward the word… and making sure the follow-through is there as well.
The singer grasps the point whether they have ever swung a golf club or not, because I have shown them the idea and illustrated it with a visual cue to which I can refer at a moment’s notice in a hundred other situations.