Along with the faceplate itself, thumbsticks are also swappable on the Valor Pro. Below are the steps in order to do so:

1. Gently pull off the faceplate from the top of the controller.
2. Grab the thumbstick you want to remove and pull it up firmly. 
3. Align the hole at the bottom of the new thumbstick with the post on the actual controller.
4. Give it a slight push until it goes into place. 
5. Put the faceplate back onto the controller.