for the servo lead, I would do like that:
Remove the elevatorplug from the receiver. Then You need to knot a (long and fix enough) string (kite-string is good) on the JR-connector and You pull the servo and the string carefully out of the fuselage. Now You just have to knot the string on the new servos JR-connector and pull the wire back again. Be careful and do not pull too hard. If You feel resistance, just pull from the servoside and try again. Good luck.