Home Button on my sons iPhone 4 was starting to work intermittently.
I had replaced this part on my own IPhone a couple of months ago so the repair was not too difficult.
This repair required precision and patients, rushing or skipping steps is not recommended. Also, having a magnetic parts template to place screws as you take them out helps a lot when it comes to reassembling the iPhone. The iPhone is not really meant to be repaired so take care working on it.