Statements such as "some part will wear out eventually" can be indeed a bit confusing. What they really mean is "that machine is moving because it's consuming e

Statements such as "some part will wear out eventually" can be indeed a bit confusing. What they really mean is "that machine is moving because it's consuming energy stored in some of its parts, and it will eventually deplete it completely". Would you argue that a car is a perpetual motion machine, provided that somebody "repairs" it by refilling the fuel tank once in a while? Same thing. A machine that moves by extracting the energy stored in one of its parts is not a perpetual motion machine, it's just a machine that runs on a very unusual fuel. On the other hand, there might well be the case of a real perpetual motion machine that needs repairing once in a while- in that case, however, it should be possible to prove that the energy stored in the part that needs replacing is not the source of the movement, either because it's not enough, or because it is going somewhere else- for example dispersed as heat.