Cut an access hatch in part 14 and fit your motor. The hatch is simply taped or covered over for retention, allowing access at a later date if required. If fitting an AXI motor, make sure that there is enough clearence for the rotating rear drum.
It is easier to fit the servos to the servo tray before it is fitted in the model. Three mini servos are ideal.
Check all linkages for free movement. The servo leads go forwards to the Rx, which is positioned behind former 10.