A late reply to this thread. But I believe many clips get returned because users aren’t use to pushing the headphone plug in with abit of force.
A friends clip actually made a nice snapping noise , the first time I plugged in her earphones. At first I thought I broke it. But it worked and was just a very tight fit. My clip was simular. Now the plug fits in without this added force. If you got muscles, use them, make sure the jack is plugged in ALL THE WAY. There should be only about 1mm gap between earbud jack insulator to the edge of the player.
If you only get sound out of one earphone , or a crackling noise (loose connection). PLUG IT ALL THE WAY IN.
I’ve seen this on several clips and this forum is loaded with people that asked the same question. Jack failure is rare, and I’m sure those who thought it was, just didn’t try to snap it in hard enough.