An Inmarsat-C terminal will not "LOG IN". A test antenna cable with a new ADE attached in view of the satellite allows the terminal to "LOG IN". What steps would you take?
Replace the AZ or EL motor in the above deck equipment.
Try logging into a different satellite with the original ADE.
Use a DVM to check the feedline between the terminal and ADE.
The antenna goes past the AZ EL of the satellite but does not initialize but you can manually point the antenna at the satellite and acquire signal. What is the most likely problem?