The opening at the base serves as a vent only. There should be an access door on the same side as the computor reset handle. Open up the access door, which is just below the computor rest handle, and there are two levers inside, one for each door. The doors are hinged. You may have to drill out the lock out of the access door but it is a simple cabinet lock available at any hardware store. If you still have trouble let me know and I can take a picyure of my pump with the door open.