Home Button intermittently working

Recently, the Home button on my iPhone 5 started working intermittently. I have recently repaired a few things in my phone (battery, volume buttons & cables) but each time all seemed to work ok. But recently, the Home button stopped functioning. Then, it would function again and then not. I tried shorting the contacts for the home button and that seemed to work which told me it was the button itself. But today I tried something new which confused my analysis and I thought I would throw it out here. I attempted to activate my phone in the normal manner with the home button. No luck so I used the soft keys I have turned on to activate the phone. While using the phone I attempted to change apps with the home button, no luck. But then I used the pwr button/home button combo to take a screen shot and it worked fine? I thought "wow, I am surprised that worked". I then tried just the home button and nothing. Then the combo and it took the picture. I did this back and forth several times with the same results. So, if my issue is the button itself then why does it work as described above? I'd love to purchase the part and repair this problem but don't want to chase an unknown problem with random new parts. All help much appreciated.....