I got a 7C5 out of my loctal bin to look at the “bump”.  Interesting - I always thought those bumps were to aid in orientation when inserting the tube (it marks the center post's key).

When I am repairing/restoring equipment using loctals, I generally do not pull any tubes unless they are suspect in some way.  If the stage is performing as I expect, I leave them be out of concern I would cause intermittents just by disturbing the pin-to-socket connections.  Now I have to worry about pulling with the right tilt, too.  Of course, in the many past decades the owners might have repeatedly pulled the tubes and loosened the sockets, so all bets are off really.

My biggest gripe with loctals has been that some sockets have excessively strong circular springs gripping the center post.  Maybe with the proper tilt that won't be the case.

For those unfamiliar with the bump...  It is on the side of the metal base (above the chassis line), as opposed to the bump on the end of the center post that goes down into the socket.  

See the attached close up picture of the bump in question…