When I was a new Dispatcher at Western, I was getting checked out on the Hawaii Desk when I got a call from a DC-10 en route to Honolulu saying that they had a trim malfunction that was causing them to porpoise. We had MX waiting when they arrived but a ramp rat found that a container had not been locked down and it was free to roll back and forth on the tracks.

Our 10s actually had lower lobe galleries with easy access to the baggage area had anyone thought to look.
Pat