I had the same problem. I lost one of the rubber bumpers on my track pad. I had a apple blue tooth key board that was not working so I removed the rubber bumpers from the key board. I trimmed away the outer edge of the bumpers so they fit neatly in the holes of the track pad. I attached the bumpers using the 3M adhesive strips that come with the little hooks you hang on your wall. I attached the key board (trimmed down) bumper pad to one side of the adhesive tape, then carefully trimmed away the excess around the bumper pads. Next I pulled the protective paper from the 3M adhesive and made some small minor shaping until it was round and the same size of the bumper pad. I attached the bumper pad to the track pad. I then did the other size so they would be the same. It worked great. No problems at this point.