[rotorwrench]

I really haven't seen a good original since all the ones I've seen are reproductions. They have a small piercing in the base socket that allows a small part of the piercing to be bent inward to hold the light socket in place in the base. If that little piece of metal shears or wears off then the light socket will come out like the OPs.

All the reproductions have to be twisted a few degrees to turn the light on or off. It seems like it has to be pushed in to turn so that it can disengage one set of bayonet lugs and then engage the other set so that it locks in place for on and for off.