How do you stop the ferrules from popping off the shank of the pipe? When I first got my lot of smokeable seconds, they seemed to be fine, but I think in this cooler weather the wood has slightly contracted and while just now cleaning about 4 of them, every single one fell off on the floor or was very loose to the point they would have come off if I didn't hold it in place to remove the stem. I know they're cheap to replace, but what's the best way to stop them from coming off? Is one glue better for it than any other?