Due to the difference in some coupler heights from different manufacturers, here is a way to make minor adjustments to the coupler height on our freight car truck.
Step 1: Remove the truck from the freight car. There is a C clip that mounts the truck to the frame of the freight car.
Step 2 Remove the small Phillips head screw near the coupler a shown below. This will allow you to separate the coupler from the truck.
(http://www.williamstrains.com/faq/step1.jpg)
Step 3 Remove the wheelset closest to the coupler. Slightly spread the sideframes to do this.
Step 4 At the point shown on the photo below make a slight bend, downward to lower the coupler, or upward to raise coupler. Only bend a little a time, it does not take much to change the height.
(http://www.williamstrains.com/faq/step2.jpg)
Reverse the steps to reassemble.