Don't use business cards, they will slip around and get out of place.
Go to a store that has Scotch double-sided foam tape (this:
http://content.etilize.com/Large/11965093.jpg), and cut it into strips that are slightly smaller than the metal bracket on top of the sensor. Once you have the pieces cut into the right size strips, put it on the metal bracket, on top of the black rubberized tape. DO NOT remove the green paper on the tape.
Repeat this with all the panels. I have it done on my machine, and it makes them feel a lot better, and helps with pad quality overall.