Chosen Solution
A few weeks ago my phone was having sound and vibration issues. Periodically, and almost always simultaneously, the vibration and sound would stop; it would usually happen while it was charging and I was using Wi-Fi (downloading apps or watching YouTube). My phone also seemed to get hotter than usual. I replaced the battery, separate issue, and while I had it disassembled I reseated the cable which connects the vibration, sound and Wi-Fi. Since then, the speakers work a little better, but now the vibration only happens when the speakers are playing. I’m thinking the next step should be replacing the Wi-Fi/vibration/speaker cable. Any thoughts?
I think that would be the next logical step, also maybe change the vibrate while your at it.