A Mechanism (n.) excludes a wheel that can be turned though nothing else moves with it.
A Mechanism (n.) whose parts are soft as butter is still a mechanism and might be used, as elastic concepts are.
A Mechanism (n.) posited in the mind or brain to distinguish reading from not-reading is only a hypothesis, a model designed to sum up what you observe.
A Mechanism (n.) is what we invent to save a difference: if not in conscious states, then in the unconscious or the brain — an internal working we imagine seeing, though no such mechanisms are known to us.
Mechanism (n.) is a misleading word in mathematics: avoiding contradiction mechanically is not mending bad mathematics but making new mathematics.