Here's a nifty trick to recalibrate your iPhone's home button if you're finding it little unresponsive or laggy. You don't need to take it apart for it.
All you need to do is follow these simple instructions:
1. Launch any app such as Stocks, Weather etc that comes pre-installed with your iPhone.
2. Press and hold the power button until you “slide to power off” appears on the screen.
3. Release the power button and now press and hold the Home button until the "slide to power off" goes away.
That's it. You will notice that it kills the app. You will also notice that the home button is a lot more responsive.