I do remember the story of a BA B757 on base training duty who could not get the gear down by any means. The solution devised (lucky they had the fuel while the tech gurus devised the solution) was to depressurise the hydraulic system which kept the gear up. Then the back up system could be used and once released aerodynamics + gravity did the rest.
You remember well. In fact story went that Gear Lever actually came off in hand during UP selection, so all gear pressurised up and solution as you posted. There was a procedure in the QRH for that for many years afterwards.
I was going to venture something along the same lines for this LOT incident but you beat me to it in a way. However I think it is possible that this incident will turn out to be gear still pressurised up as that would be the only common link. Perhaps the selector valve stuck/trapped in UP position? Cable snapped after UP selection? This would preclude Gravity procedure.
Just a couple of thoughts.
Not quite correct, I know 'cos I was there... 21st May 1985
During base training, on selecting the gear up a bolt in the gear linkage had worked it's way out (never had a nut on it!!) This left the gear selector not connected to anything (although we didn't know it at the time) and the gear itself being powered up irrespective of any uplocks being removed and gravity(emergency lowering) supposedly taking over.
It was a team effort within the a/c (no "fixes" from the ground engineers). The hydraulic system that was powering the gear up was depressurised and the gear dropped and locked down under gravity. However, even though all pumps were selected off there was slight flow, enough to unlock the main gear (braces moving from locked over centre position). This was overcome by dissipating the pressure/flow from the pump by cycling flap selection on the approach.
At that time Boeing still had a resident engineer at LHR who was rather embarrassed when microscopic examination of the bolt that "fell out" showed it had never had a nut fitted.
If anyone wants further information I still have the ASR report. Ironical that having flown the Trident for over twenty years with not a single problem with the U/C, the first time (base training) with it now being called the Gear we couldn't get it down!!