You don't need to take it completely apart, just remove the belt clip and phillips screw, and the four T-6 screws from the back of the case, then separate the case enough (maybe a 1/4" at most) to be able to get the door, hinge, and pin into the right spots which are pretty straight forward where they go. The "shorter" arm of the spring goes on the door side, the "longer" arm fits into a slot on the one side of the transmitter case.
Hopefully you are mechanically adept, otherwise find a repair place to do it for you. This assumes you are outside your warranty and on your own if you break something.
