DeWalt D25481K Manual page 92

If there is a line between the boundaries as shown below, a repolarization will have
taken place, with the following consequences, the armature has been damaged
and has to be replaced. It is mandatory that all areas of the four pole ferrite-magnet
ring is checked for failure.
H
H
Very important information
Clear indication of the that pole ferrite-magnet
ring has repolarization