I recall B757 incident (BA in early years of ops) had a gear lever detach completely in pilot's hand and this with gear selected up!!! This of course meant gear was pressurised up and alternate gear extension not possible as system should be depressrised to allow freefall. Simply switching pumps off wouldn't help as "up pressure" was trapped in line.
Seem to recall crew in coversation with their engs and Boeing in Seattle came up with a fix involving manipulation of hyd systems to allow extension.. A procedure appeared in the QRH and remained for a few years. Guess permanent fix for "detachable gear levers" removed the need for procedures.
