It might be folklore, but back when I ran S-100 bus crates in the lab,
it was regular practice to unseat/reseat boards periodically to keep
things working.  I have done that on other machines, too.  I only have
dropped a machine a time or two, as a last resort  (peecee crates).
Sometimes the jar worked...... sometimes it didn't...... (:+}}.....

I had a good friend that had a big Navy radio transmitter that did
some periodic shennanigans.... he kept a big rubber mallet aside
the critter, and if it acted up,   WHAP!  upside its head, and that
would jar a sticky relay into action.  I have often wondered if that
would work on computers.... (They did sell a big foam baseball
bat, called a Byte Bat, for whapping computers upside the head.
Haven't seen those since the early 80's, tho.....).

Tales to tell.....

Bob