The Atlas couplers have 2 screws that share the same threaded hole. To fix your droopy coupler:
1. Remove the truck from the car.
2. On the bottom of the truck, loosen the screw that hold the uncoupling armature. This is the screw that goes through the coil spring.
3. On the top of the truck, tighten the screw that holds the coupler to the truck. The screws in steps 2 and 3 share the same hole so if the bottom screw is too tight, you won't be able to tighten the coupler mounting screw on the top.
4. After the top screw is where you want it, tighten the bottom screw.
This method has worked for my Atlas cars that occasionally develop a loose coupler.
