Fixing things the hard way. Success! Still, I am an idiot.
Suddenly one day, my headphones stopped wanting to stay plugged into my iPhone. Nothing exciting, dangerous, or out of the ordinary happened to my phone. I was baffled--I would plug my headphones into the headphone jack, and no matter how hard I pushed, I could not achieve that satisfying "click" indicating the headphone connector found its home, and I could enjoy my podcasts.
In my pocket the headphones would fall easily out of the jack. In my hands, while firmly holding everything in place, all audio would stop as though the connection to my earbuds had been interrupted. Occasionally I'd plug in my headphones, only to serenade my lab with the sweet sounds of "Wait Wait, Don't Tell Me" at full ringer volume. This problem had to be fixed.
Total time: 3 hours.
As advertised, the repair was difficult. Tedious. Tweezers and steady hands a must. The photos in the repair guide were very helpful, but by no means conclusive. It went about as well as I thought it'd go, maybe a little better. I'm sure if i ever feel the need to nearly completely disassemble my iPhone again, it'll be faster...maybe not any easier though.
In the end, I found the problem. After completely replacing the headphone jack, I autopsied the old one and found the culprit: an embarrassingly large and well-compressed piece of pocket lint stuck to a bit of adhesive at the bottom of the headphone jack. The adhesive is there to keep things from falling all the way into the phone, but depending on the debris, it might keep it in the hole too.
Pay special attention to the ribbon cable and how its wrapped around the volume button shelf and mute switch assembly! That thing is a tricky, tricky, beast to reassemble.
Tweezers. Get them now.
Be organized. During disassembly, lay out your parts neatly, and pay attention to the orientation of things as they come out of your phone.
Be patient. You're going to drop a screw and spend 5 minutes searching for it, only to realize it fell into the phone and wedged itself under a logic board. You'll find it.
Check for lint.
P2 Pentalobe Screwdriver iPhone
iPhone 4 (CDMA/Verizon) Headphone Jack & Volume Control Cable