Now I have gone over things for the nth time I see that the fixings for the antenna socket are a little loose, and in fact its mounting to the printed circuit has broken free. The central pin seems OK, just the mounting for the outer brass shield is loose
Some truly kludgy soldering has gotten things working OK, at least long enough to see if this card is any better than what I was using before.
If not then I would still be keen for suggestions.
A (qualified) Sorry to Netgear!