You can get a little tube of this at home centers - Locktite. Now, be careful, read the label, there are several types. Pick the wrong one, and it will be a bear to take out, but the blue stuff works pretty well for this. Double check, cause I haven't bought any for awhile, and they may have changed the color scheme! It is a liquid you put a drop on the threads, tighten it up and then let it sit until it sets. It becomes a plastic that holds the threads so it doesn't move. The red stuff locks it down, and you might strip the head when trying to remove it. So, again, read the label to make sure you get the version that CAN be taken apart, if you want to.