All the pins are out and cables are loose, and the gearbox is free to come out.   Except the receiver seems too small to allow it.   Sliding the gearbox as far forwards as possible, the rear is still a good 5mm inside the receiver.       OK, so let's tilt the gearbox up and take it out at an angle.   Note the lip on the receiver where the bottom of the gearbox can slide into if I can... just... get it ... another 5mm....