How do I lead a team when I can't fix the problems with my own hands?

You used to fix the broken thing with your own hands. Now you answer for a whole system's failures through other people, and you cannot just reach in and repair it yourself. That distance is maddening for someone who knows exactly what is wrong. This is the real shift into leadership, and it is uncomfortable on purpose. Your job is no longer to fix the pipe. It is to build the people and the process that fix it without you. That means teaching what you know instead of doing it, which is slower and feels worse at first. Pick one person on your team and pour into them what took you years to learn. When they solve something the way you would have, you will feel it: your hands are still on the work, just through someone else. That is the leverage you traded up for.