For those of you following the saga of the floppy faucet, you'll be glad to know we had a breakthrough this afternoon. Teamwork and the application of liberal amounts of penetrating oil and silicone spray loosened the nut enough to allow Matt's spanner sufficient purchase to wrench it off.
With Kathleen squeezing a man-sized pair of adjustable pliers above and Stan grunting and turning the copper nut below, the reworked assembly zipped up the center shaft and now has been firmly tightened against the silestone, hopefully making the faucet shaft stand erect and firm for the rest of our days here.
What is left to do is a leakproof reconnection of the waterways and the spray device. Let's see, was that hot on the right and cold on the left?