why is the motor amature sparking?

the brushes will need to be "bedded" to suit the shape of the copper part of the motor
first make sure you unplug the mains supply.
you will need glasspaper to do this
lift each brush in turn
place the glass paper rough side towards the brush then let the brush back to its normal position.then gently rock the armature back and forth to allow the brush to be shaped by glass paper
repeat for other brush
then remove paper blow out all traces of the abrasive material and carbon dust
reassemble vacuum and test
if this does not improve the sparking you will probably need a new motor

chris
January 2009