Headphone jack cable replacement.

I am considering the headphone jack/ mute-volume switch assembly from ifixit. I have a iPhone whose mute switch doesn't work correctly.

I've purchased the same part from ebay, and twice the 'new' part, and in both cases the mute switch worked (not great but better), but the headphone jack didn't. (the phone thought headphones were plugged in all the time, and then speakers quit)

Is this a common problem/ mistake made when replacing this, or was I getting bad parts?