Hi Keith,
I can't find that you've posted any information about the age of your boat, but assuming she's a Reedcraft boat then there is no reason for one locker being more difficult to remove than the other.
Both should simply be fixed into place with self-tapping screws (I have seen some riveted, but I think that was an owner embellishment) and sealed with something non-permanent. (I use "Plumbers Mait").