What you are looking at is not a Voltage Regulator, it is a dual circuit breaker. You will find no fuses in the Lincoln \, unless some circuitry was added by a previous owner. Lincoln "L" did not have a voltage regulator. If motor-generator is not charging the battery properly, look into generator brushes, also make sure the field energizing wire is properly connected to the ignition switch, and all intervening connections are clean and tight. This is a unique system, shared by Cadillacs of the same years.
You need to order a service manual and set of 1924-1930 service manuals from LOC.