A 68-year-old man with COPD is intubated in the ICU for respiratory failure. Post-intubation chest X-ray shows the endotracheal tube tip positioned 28 cm at the incisors. On examination, the patient has asymmetric breath sounds with diminished left-sided air entry and elevated airway pressures. The structure marked **A** in the diagram is the likely site of tube malposition. Which of the following is the most appropriate immediate management?