Explanation: When an Inmarsat Fleet Broadband antenna continuously changes azimuth after initialization, it indicates a problem with maintaining its lock on the satellite. * **B) Use the Web interface to check the event log:** Modern satellite communication systems are highly sophisticated and self-monitoring. The Web interface provides access to the terminal's internal diagnostics, including the event log. The event log records errors, warnings, and operational events that the system has detected. A continuous azimuth change is a critical tracking failure, and the system's internal diagnostics will almost certainly log relevant information (e.g., "loss of signal," "motor error," "sensor fault," "GPS error") that points to the root cause. This is the most logical and efficient first step for troubleshooting a complex electronic system. * **A) Replace the gyro repeater motor in the Antenna Tracking Unit:** This is a specific, hardware-replacement action. It's premature to replace a component without any diagnostic information confirming it's faulty. Furthermore, many modern Inmarsat terminals rely on internal GPS/compass rather than an external gyro repeater for initial pointing and tracking, making this option potentially irrelevant or a misdiagnosis without further information. * **C) Check the EL step motor with power off:** EL refers to Elevation, which controls vertical movement. The problem described is with *azimuth*, which is horizontal movement. Checking the elevation motor won't directly address an azimuth issue. Also, directly inspecting hardware is usually done after exhausting software diagnostics or when specific error codes point to a mechanical failure. * **D) Check the integrity of the antenna interface cable:** While a faulty cable could certainly cause communication or signal issues leading to tracking problems, checking the event log (Option B) would be the *first* diagnostic step. The event log might report communication errors, signal loss, or other symptoms that *could* be caused by a cable issue, thereby guiding the technician to inspect the cable. Without checking the logs first, inspecting the cable is a speculative action.