1. What can I do to help us work together more effectively?
2. Is there anything I'm not noticing or paying enough attention to that I should know?
3. What should I know about your workload that would be helpful to you?
4. Is there anything I'm doing -- or not doing -- that's de-motivating?
5. What (more) can I do to help you with your goals and your career?
Use them sparingly: Best asked separately (not all five at once) and periodically
When the possibility of asking them comes up in discussion with my coaching clients, I hear a spectrum from, "No way I'm going to ask this," to "If I ask this, I'm going to have to do something about it,"
The latter response comes from more secure leaders. You have to have a healthy ego to ask blind spot questions and hear the answers with an open mind. When they use the questions, my clients have found they have yielded great results.
Try one or two. If you avoid any defensiveness or debate, and hear them out, the results will be well worth the effort.