Its pretty simple. You need to open the shelf of a battery. You can do it only with some strong screwdriver and lot of force. You will need to destroy the package. Be sure to destroy the softer side of a package. That one on which the cable is sticked in. After you will finish you will end up with something like this (cable is already removed): Then you use the soldering iron to remove the cable. You may want to use desoldering suction pump to clean the contacts. Otherwise it will start overheating very fast. It will also leave you with clean holes, so putting there exchanged cable will be much easier. As you can see on a photo, the three control cables are marked. One has a grey strip on it, one has black strip on it and third one is clean. So be sure not to mix these three cables. Be aware, if this will destroy your mac, I'm not the one responsible for it :-D Maybe even mine will burn up one day :-D But so far still no issues with my battery. Lucky me :-)
I had the same/similar problem. My battery "got pregnant" and was pushing out to the touchpad. So I decided to replace it. Unfortunately I bough battery for newer version of MacBook Pro (15"). I was too lazy to return it and order new one, so I searched for another solution. I came across this thread where pinouts were written. After small research (or I should rather call it experimenting) I found a solution :-) The above answer where you cut the fatter connector to fit is wrong. If you would look closely you will see that the + and - pins are reversed between these two connectors. On each connector there is a mark for + and -. So cutting it down wont help. If you have both batteries, you need to disassemble them and exchange connectors between them. The control pins are on both connectors same. So while one connector has pins in this order [code] the other has pins reordered [code] Be aware! Without proper tools (like soldering iron, etc) and at least some technical skills you wont get too far. I...