I've done a few actually. I think pretty much all of them worked. You don't always have to replace all the caps. There are two types in particular which tend to fail. The 1000mF and 1800mFs. It does vary. Some of these boards do have up to a couple of dozen of the bad ones, but many have only 6 or so. Given the time it takes, it could be considered overkill to replace caps which aren't bulging or leaking. I've gotten away with leaving the odd one here or there.
You'd need to take the bottom case off. First inspect the battery to see if its swollen at all. If not, there should be a tri-wing screw on the underside of the trackpad. Adjusting this can affect the click, you'll have to experiment a bit. And you'll need a tri-wing screwdriver obviously.
