Hey there. We've noticed some relatively small puddles on our basement floor, and have determined that the water is coming from the floor above, from the bathroom on the main level. (Not sure how long this has been happening since the water was found in a space we don't really use often.) After many tests, we see that the leak happens when our showerhead (with hose) is hanging down into the tub, not so much when the head is in its place. Is this as simple as cleaning a gasket and/or replacing the showerhead, or is there something more I can do?

I appreciate any feedback--thanks!

I don't think the leak is your shower head, especially if it is hanging into the tub area. Chances are you mixer valve or the pipe coming up from the valve are the source of the leak. They have pressure only when the shower is turned on. Can you inspect the wall cavity from below? If not remove the mixer valve cover and inspect with a flashlight. I think you'll see your leaking area.

Best guess, the seal around the tub spout needs to be fixed. When the shower head is down, it's forcing water along the wall and around the spout. When I installed mine, I used plumbers putty.

Another possibility is that it's leaking into the overflow which is at the bottom of the drain lever. This I think is unlikely.