My son's problem appears to be fixed. Sort of. We've been watching it for about 10 days now to be sure it doesn't stop working again. Having enough technical background to understand what took place, here's what was done.
First the tech replaced the wireless card. No change. Then he replaced the antenna (just the physical antenna housed behind the screen), no change. Then he replaced the interface from the antenna to the motherboard. Change. This is a long black rectangular box item that sits below the keyboard and is surrounded by several components. Small cables in and out.
Once changed the laptop started working as it had the first three weeks my son had the machine. I say that because even then the machine didn't 'find' as many available connections as any of our other machines, and the signal strenghth was never as good as our other electronics in the house, but it worked. And it does again.
After watching the repair and given the location of this 'part' my best guess is that the problem is heat. This particular part is surrounded by other electronics and the ventilation is pretty limited. So my son is being careful about setting the machine down on his bed or a chair when it might not be able to get enough air through the bottom ventilation.
He now has his bluetooth back, his speed is solid, if just a little slower than his Sony Vaio and my own Dell, and he can work from anywhere in the house.
I only say sort of at the start of the post because the speed is off a little and he still doesn't appear to receive (find) as many available connections as every other piece of technology in the house, but it works.
So let me say thanks to Terry for taking notice and getting involved.
And let me just say - I still believe this is a design problem. Either the component replaced was (or still is) of poor quality, or the location of the component (where it can easily overheat) is the true design problem.
Thanks again, Terry.