You can compare the strength of the old and new bar by checking with the fingers how strongly they attract a steel part.
Or if you want figures, suspend the bar under a thin thread, and measure the oscillation period in the geomagnetic field. Compute the inertia, deduce the magnetisation. If the stable position doesn't depend on one turn more, the torque results from the geomagnetic field, not from the thread.
The unstable movement could better result from the alteration of the coefficient of friction, or from a beaker with inadequate shape at the bottom. Maybe from a bar and a motor not meant to work together.