While I am unfamiliar with this paricular aircraft and I'm sure someone will chime in with your repair concerns, I will adress your other concern. The fact you are doing this with your son is wonderful. get the plane fixed and keep it up. It will be a memory he will cherish for a lifetime and dues paid by you that will come back 100 fold. These model planes... all of them will crash. More so when you are new at the game and a little less as you go. If you and your son are not members of a local club, concider joining one as there are many people who will give you face to face help and happily do so. The rewards of becoming a member typically make the nominal fee for membership unimportant.

With that said, I downloaded the manual for the E-Flight Apprentice and see that it is a foam construction aircraft. Most if those planse use a silicone gel like material to keep the servos in place. this is the same as the clear RTV gasket sealer you can get at your local auto parts store. If the existing servos look like they are held in by a rubbery material then go to your local auto parts store and ask for clear RTV gasket sealer and get that kid flying again... and yourself too. Welcome to RCU.