I never repair such a part. I only replace it. And let me be clear, I have never found bits and pieces for the entire pad and buttons.
Last week I took apart my HP dv6t-1200 laptop to clean a very dusty fan, then reassembled. After reassembling, the left mouse button "collapsed" - it sits a teensy bit lower than the right button. The left edge is a tiny bit lower than the right edge (which is lower than the right mouse button). It still responds, but the click is much less "tactile".
True confessions: after reassembling the laptop, I have maybe three or four leftover screws, along with a round... thingy. A piece of plastic, shaped like a tiny cylinder, maybe a quarter-inch in diameter and a quarter-inch in height?
The computer actually works fine, and this is only a very slight annoyance. Touch-tap also works fine. I'm thinking about opening the computer back up to see if I can repair the mouse. Does anyone have experience with this issue?