I recently replaced a laptop key due to the paint scratching away. It went fine, except now the key in question feels softer and spongier than other keys.

I am sure the mechanism (hinge) is in place correctly, and the key is surely the cleanest now since I've popped it open and cleared the inside. What's caused this sponginess? Did I damage something when taking out the key?

I've got a replacement hinge, and will try again. Any tips on how to prevent scratching of other keys would also be appreciated.