A 52-year-old female with rheumatoid arthritis and ankylosing spondylitis is scheduled for emergency cesarean section. Awake fiberoptic intubation is planned due to severely restricted neck mobility. The fiberscope is passed through the nose, and the vocal cords are identified. However, when the endotracheal tube is advanced over the scope, it catches at the level of the arytenoids and cannot be advanced further despite gentle traction. The fiberscope is still visible through the tube lumen. What is the most appropriate next step?