When I worked at Disney waaaay back, the Lincoln animatronic in HoP lost hydraulic pressure and slowly tipped forward until it was nearly in half. Since it was designed to stop if Lincoln fell backwards (there apparently is a sensor in the chair if it gets hit or broken) the show did not auto E-stop However the face was controlled by air pressure and kept moving and talking. It was quite bizarre. The cast member came in and literally screamed and then (I assume) hit the E-stop and the show abruptly ended. (Not a malfunction but there was a notorious time they put Mickey Mouse ears on Nixon...)