Here are some solutions to common mistakes trainers make when performing this move.
The Flaw: Not achieving full contraction.
The Fix: The typical culprit here is going too heavy, which limits your range of motion at the top and keeps you from squeezing your shoulder blades together and properly thrashing the muscles of the middle back. Lighten the load and make sure your hand comes to at least chest level. Your elbow should bend well beyond 90 degrees with this move.
The Flaw: Planting your foot too close to the bench, which compromises balance.
The Fix: With one knee up on the bench, place the other foot two to three feet off to the side and slightly in front of your planted knee. This is a more stable position that allows you to pull more weight. When rowing with your right arm, think of aligning your left hand and knee (both on the bench) and right foot (on the floor) like a tripod.
The Flaw: Opening the chest.
The Fix: Yes, pulling the dumbbell high for a full range of motion is good, but not if you do it by twisting your torso to that side. Keep your chest facing down throughout the move. At the top your shoulder will naturally open a bit as you contract hard to pull your scapula in, but there should be no rotation in your lower torso.