Why isn't the Oxford Electric Bell considered as an object in perpetual motion?

The Oxford Electric Bell is a set of bells where a metal ball moves back and forth due to the charge that is administered to keep the ball going back and forth. That means that it continues to ring. However, there have been a few instances since 1840 when it stopped ringing due to weather issues that affected it.

You really can’t hear the bell anymore since it is enclosed in thick glass. It can be found in England in the Clarendon Laboratory. Perpetual motion is a scientific term that refers to a body that is always in motion. However, the Oxford Electric Bell is not considered to be an object in perpetual motion due to the fact that it could stop moving.