I would make sure that the home button comes flush with the screen. If it does then I would disassemble it and check the home flex that is underneath the physical button. If you can't fix it by cleaning I would recommend that you replace the home flex first and if that doesn't work then try the charge port maybe.
Hope this helps.
P.S. Not repairing the iPhone 5 or below? The 5s, 5c and 5 are almost identical and not to be a debby downer but the iPhone 6 isn't going to be any easier to repair. I would recommend lots of patience and practice. Never give up on repairing something no matter how tough it is. This is how you become a better tech!!! :)