Ask anyone who repairs any kind of machine for a living. Demons, or gremlins, or something, exist in every complex mechanical device ever made.
I specialized in Lincoln & FoMoCo air suspension and ran our site tech line. I went above the FoMoCo tech manuals of how the systems worked and electrical problems their computers developed as they got older.
I coined one problem for 1984-92 Lincolns as Demon Possession with the symptoms being Linda Blair controlling the vehicle while parked.
There was a quick test for Demon Possession with solution being to replace the suspension module.
We had inert slugs on a gas carrier I sailed on.