Vaio Z51 dissappeared WLAN hardware

Firstly, I have a VGN-Z51WG, with 6gb RAM, running Win7.

Since a few weeks ago the WLAN occasionally stopped functioning, but it has gotten really bad in the past few days. As far as I can see it is NOT a software problem: the WLAN simply dissappears in devise manager altogether, and I can't see it with a system recovery boot disc either. WLAN also doesn't show up in Sony Vaio SmartNetwork, although WWAN and Bluetooth are still there.

Note however that the physical Wireless switch (next to the removable media slots) are still on and lit, and can still be turned on and off normally.

A few days ago, the WLAN will come back if I tilt the laptop or press down on the left palmrest, but this trick no longer works and WLAN seems to be gone permanently.

Any advice on fixing this would be much appreciated. I'm prepared to eventually open up the case and look at the hardware, but I'd like to have a good idea of what to do before I do so -- I'm not a complete novice but I'm fairly inexperienced with notebook dis/assembly.

Thanks!


EDIT:
Seems to be the same problem as these:
http://forum.notebookreview.com/sony/398073-vaio-z-disappearing-wlan-hardware.html
http://forum.notebookreview.com/sony/465674-sony-vaio-z-540-wireless-problem-intel-5100-agn.html
Unfortunately, no clear result was posted there.