Surface 2: Home button not springing back in position.

As the title states, the home button on my surface 2 is jammed and won't spring back.

I performed a battery replacement which required me to remove the motherboard, and after replacing everything back in its original spot the home button refuses to be springy.

Taking a closer look at it, it only has a plastic piece between the button and the switch. I see no sort of spring mechanism, and I don't have any spare pieces laying around.

Am I missing something? How do I fix this?