I know there is a a pair of small clips that go in to keep tension on the pads. Rest against the caliper and helps to hold the pads in proper position. I didn't think these of any importance as I had one cracked and all seemed fine. That is until I changed out brakelines and changed pads simultaneously. When bleeding the lines I just couldn't get the front bakes to bleed correctly. After much frustration and cussing, I discovered that this clip was snapped such that it was holding the pad in a position where one of the pistons couldn't operate properly preventing the brakes from being bled. Replace the clip and all was well. Don't know if this is your problem with the uneven wear but might be worth taking a look at.
