Anyone have a cure for a front lens cap that won't stay on tight? It's on a CF lens with standard 60mm bayonet. Problem is with the lens, not the cap. Owning 4 CF lenses with the same bayonet mount, all the caps fit tight on the other 3 lenses, and none of the caps fit tight on the culprit lens. I don't see any visual distress in the lens bayonet. One day I fear it will be gone, lost on a trail somewhere. Any suggestions?