No heres what you do, you cut the cord off that old saw and go to WAL-MART and buy you a new saw. $34.98 will fix the problem oh and brushes includes.
Mickey-G TN, July 2008
This maybe due to new "square" brushes settling into the older "worn to a shape" type armature, if sparking still occurs after a bedding in period (which maybe seen to go round the armature in rings) then suspect a defective winding in the rotor.
If you can run the motor (minus the blade) and get access to the armature you can use a comm. stone to clean the armature and bed brushes simultaniously as the motor runs.
If a winding(s) in the rotor is defective it's generally a bin job
Jac Flash, July 2008
cleaning never hurts,or undercutting the segments,butsparks are just caused by the new brushes conforming to the diameter of commutator.they will bed in eventually.some carefull filleing of brushes will speed up process.
caine, July 2008
edit
I can answer this question...
Why the sparks after I replace brushes in skilsaw?
