It's now many many years since I did mine. Mine was with filled with sand so I took it apart. Now that spring, yep I had difficuly with that. Although the lock worked fine you had to return the key to center so I eventually took it to a locksmith. I think he charged me a fiver, how long ago ?. I screwed mine together with vountersink screws and nuts. Yep is's still working but the key still has to be returned to center by hand
ps, I thought that there was a gasket between door and lock.
In Namibia and Botswana I sealed the outside door face at the lock with masking tape