Hi All,
I just got same problem today.
When you press on tho the headphones, because of vacuum you will slightly move membrane. okay, as soon as you will remove padded portion (little flat screwdriver between padding and plastic and just carefully lift it until it pops up and do it on all 4 sides) you will be able to see membrane (speaker).
If you look closely, there is copper thin wire under membrane which goes from center onto side. if you take something non metallic/magnetic and slightly press around side of the membrane where copper wire is, you will see it will play. I guess this is due to poor design and wire just get snapped. Anyhow as previously said, if you put small piece of cotton or something really soft under plastic meshing so it press slightly on side of membrane where wire is, it should be working. For how long, Ive no idea, I just done it today. btw, this should qualify as replacement because of bad design and obviously this is failing point, shouldn't it?. cheers