Also, to the person having trouble swapping pads:
It is super easy really. Pinch the edge of the pads and gently tug away and look for one of the plastic tabs that is holding it to the cup (you won't see it). You'll know you have one when no space opens between the pad and the cup. There are four of them (at 12, 3, 6, and 9 O'clock relatively speaking), but you only need to get one to pull off.
Pinch at that point, and then feel around under the pad until you detect the "ring" that connects to the cup / pad. Press down with a firm but gentle grasp and push down (like you want to deform the circle into an "oval". You should feel/see the plastic tab (shaped like a hook) release. Then just pull up and the whole pad should come off nice and easy.
To put the pads back on, gently "slide" the pad back in to the cup. You should be able to get 3 of the 4 tabs in without any special maneuvering. When you accomplish that, gently pinch the top and bottom of the ring and forcefully bend it so the last tab can "scoop" itself into position like the other tabs. I did all my pinching and pulling from "12 o clock".
The whole operation is fast and pretty straight-forward. You shouldn't have to manhandle the things.