The elevation/ depression on a HL is handled by a separate gear box as you must know but its is powered by one wire that that attaches to airsoft or recoil mechanism on the main gun motor while the second wire to the elevation motor is not. I think if I remember correctly that the wire you need connected to the main gun motor will be black.
These wires are very fine and often come loose if not held in place by the small plate that screws into the side of the main gun motor.
Look for a wire end with no insulation on it on main gun motor that has is still there but has no wire running to it (will normally be I think on the side of the motor that has black wire soldered on). Take the wire that is loose that leaves the elevation motor and re solder it to the main gun motor. Then make sure you run the wire under that small cover plate or it will very quickly brake again as the gun elevates and depresses.
Hope this helps you.
