Just to clarify are you saying the actual gun is "drooping" or bent in some direction? The cold water trick will work for that. If your saying the gun is loose on the vehicle and won't stay pointed up then that is another matter. If the gun is loose to the vehicle you might be able to wind some thread up around the base of it if you can pull it out of the vehicle without breaking the tabs. I don't have any vehicles where they are accessible as they have been packed in the attic for years now, but I think these guns were hard to get out without breaking the tab in some way, which is what section 8 is referring to.
I have caviar dreams and McDonald's pockets