Well, I succeeded in "fixing" the main "Neo M8N" GPS module by delivering 3.3 volts at the point where the "Neo" module's Vcc-RF pin would have delivered it and it appears to work. I checked previously with a meter that, with no antenna connected, there was no current flowing between the points I bridged. It is still a mystery, however, what has gone wrong to make this necessary.
The results from the ublox u-center. The GPS module was just on my desk :
and the "fix". Note the bridge between C1 and R4 :
